@inproceedings{Adorf92.1,
   author    = {Adorf, H.M. and Hook, R.N. and Lucy, L.B. and Murtagh, F.D.},
   title     = {Accelerating the Richardson-Lucy Restoration Algorithm},
   booktitle = {4th ESO/ST-ECF Data Analysis Workshop},
   year      = {1992}
}


@article{Alcock93,
   author    = {Alcock, C. and Akerlof, C.W. and Allsman, R.A. and Axelrod, T.S. and Bennett, D.P. and Chan, S. and Cook, K.H. and Freeman, K.C. and Griest, K. and Marshall, S.L. and Park, H-S. and Perimutter, S. and Peterson, B.A. and Pratt, M.R. and Quinn, P.J. and Rodgers, A.W. and Stubbs, C.W. and Sutherland, W.},
   title     = {Possible gravitational microlensing of a star in the Large Magallenic Cloud},
   journal   = nature,
   year      = {1993},
   month     = {October},
   volume    = {365},
   pages     = {621}
}


@article{Aubourg93,
   author    = {Aubourg, E. and Bareyre, P. and Brehin, S. and Gros, M. and Lachieze, M. and Laurent, B. and Lesquoy, E. and Magneville, C. and Milsztajn, A. and Moscoso, L. and Queinnec, F. and Rich, J. and Sprio, M. and Vigroux, L. and Zylberajch, S. and Ansari, R. and Cavalier, F. and Moniez, M. and Beaulieu, J.-P. and Ferlet, R. and Grison, Ph. and Vidal-Madjar, A. and Guibert, J. and Moreau, O. and Tajahmady, F. and Maurice, E. and Prevot, L. and Gry, C.},
   title     = {Evidence for gravitational microlensing by dark objects in the Galactic halo},
   journal   = nature,
   year      = {1993},
   month     = {October},
   volume    = {365},
   pages     = {623}
}


@article{Bah80.1,
   author    = {Bahcall, J.N. and Soneira, R.M.},
   title     = { },
   journal   = apjss,
   year      = {1980},
   volume    = {44},
   pages     = {73}
}


@article{Bah92.2,
   author    = {Bahcall, J.N. and Maoz, D. and Doxsey, R. and Schneider, D.P. and Bahcall, N.A. and Lahav, O. and Yanny, B.},
   title     = {HST imaging of the large-redshift gravitational lens candidate 1208+1011},
   journal   = apj,
   year      = {1992},
   volume    = {387},
   pages     = {56-68}
}


@article{Bah92.3,
   author    = {Bahcall, J.N. and Maoz, D. and Schneider, D.P. and Yanny, B. and Doxsey, R.},
   title     = {HST imaging of the large-redshift gravitational lens candidate 1208+1011},
   journal   = apj,
   year      = {1992},
   volume    = {392},
   pages     = {L1-L4}
}


@article{Bland89,
   author    = {Blandford,R.D. and Kochanek,C.S. and Kovner,I. and Narayan,R.},
   title     = {Gravitational Lens Optics},
   journal   = {Science},
   year      = {1989},
   month     = {august},
   volume    = {245}
}


@article{Bland92,
   author    = {Blandford, R.D. and Narayan, R.},
   title     = {Cosmological applications of gravitational Lensing},
   journal   = annrev,
   year      = {1992},
   volume    = {30},
   pages     = {311-58}
}


@article{Blandford87.2,
   author    = {Blandford, R.D. and Kochanek, C.S.},
   title     = { },
   journal   = apj,
   year      = {1987},
   volume    = {321},
   pages     = {658}
}


@article{Boy88.1,
   author    = {Boyle, B.J. and Shanks, T. and Peterson, B.A.},
   title     = {The evolution of optically selected QSOs - II},
   journal   = mnras,
   year      = {1988},
   volume    = {235},
   pages     = {935-948}
}


@book{Bracewell86a,
   author    = {Bracewell, Ronald N.},
   title     = {The Fourier Transform and Its Applications},
   year      = {1986},
   editor    = {Bracewell},
   publisher = {???},
   edition   = {2, revised},
   pages     = {465}
}


@book{CCDs89,
   key       = {CCDs conf.proc.89},
   title     = {CCD's in astronomy: proceedings of a conference held in Tucson, Arizona, 6-8 Sept. 1989},
   year      = {1990},
   editor    = {George H. Jacoby},
   publisher = {San Fransisco: ASP},
   series    = {Astronomical Society of the Pacific conference series; 8},
   note      = {xvi, 407 p.}
}


@book{CCDsII,
   key       = {CCDs II-90},
   title     = {CCDs in astronomy II : new methods and applications of CCD technology : a meeting held ad the Collage of Charleston, SC, March 15-17 1990},
   year      = {1990},
   editor    = {A.G. Davis Philip, Donald S. Hayes, Saul J. Adelman},
   publisher = {Schenectady, N.Y. : L. Davis Press},
   series    = {VAN VLECK series 10},
   note      = {xvii, 300 p.}
}


@article{CPT92.1,
   author    = {Carroll, S.M. and Press, W.H. and Turner,E.L.},
   title     = {The cosmological constant},
   journal   = araa,
   year      = {1992},
   volume    = {30},
   pages     = {499-542}
}


@book{Chui92a,
   key       = {Chui92a},
   author    = {Chui, Charles K.},
   title     = {An introduction to wavelets},
   year      = {1992},
   publisher = {Boston: Academic Press},
   series    = {Wavelet analysis and its applications ; 1},
   note      = {x, 266 p.},
   pages     = {266}
}


@book{Chui92b,
   key       = {Chui92b},
   title     = {Wavelets: a tutorial in theory and applications},
   year      = {1992},
   editor    = {Chui, Charles K.},
   publisher = {Boston: Academic Press},
   series    = {Wavelet analysis and its applications ; 2},
   note      = {x, 729 p.}
}


@article{Chwolson,
   author    = {Chwolson, O.},
   title     = { },
   journal   = an,
   year      = {1924},
   volume    = {221},
   pages     = {329}
}


@article{Cla94.1,
   author    = {Claeskens, J.F. and Surdej, J.},
   title     = { },
   journal   = aa,
   year      = {1994},
   note      = {in preparation}
}


@article{Crampton92.1,
   author    = {Crampton, D. and McClure, R.D. and Fletcher, J.M.},
   title     = {HRCam survey for closely spaced gravitational lenses},
   journal   = apj,
   year      = {1992},
   volume    = {392},
   pages     = {23-34}
}


@article{EEP88.1,
   author    = {Efstathiou, G. and Ellis, R.S. and Peterson, B.A.},
   title     = {Analysis of a complete galaxy survey - II:The field-galaxy luminosity function},
   journal   = mnras,
   year      = {1988},
   volume    = {232},
   pages     = {431}
}


@article{Einstein,
   author    = {Einstein, A.},
   title     = { },
   journal   = sc,
   year      = {1936},
   volume    = {84},
   pages     = {506}
}


@article{FT,
   author    = {Fukugita, M. and Turner, E.L.},
   title     = {Gravitational lensing frequencies: galaxy cross-sections and selection effect},
   journal   = mnras,
   year      = {1991},
   volume    = {253},
   pages     = {99-106},
   note      = {(F\&T)}
}


@article{Fab76.1,
   author    = {Faber, S.M. and Jackson, R.E.},
   title     = { },
   journal   = apj,
   year      = {1976},
   volume    = {204},
   pages     = {668}
}


@article{Fried22,
   author    = {Friedmann, A.},
   title     = {Uber die Krummung des Raumes},
   journal   = {Z. Phys.},
   year      = {1922},
   volume    = {10},
   pages     = {377-386}
}


@article{Gott89.1,
   author    = {Gott, J.R. and Park, M.-G. and Lee, H. M.},
   title     = {Setting limits on $q_0$ from gravitational lensing},
   journal   = apj,
   year      = {1989},
   volume    = {338},
   pages     = {1-12}
}


@article{HB93.1,
   author    = {Hewitt, A. and Burbidge, G.},
   title     = {A revised and updated catalog of quasi-stellar objects},
   journal   = apjss,
   year      = {1993},
   volume    = {87},
   number    = {2}
}


@article{Har90.1,
   author    = {Hartwick, F.D.A. and Schade, D.},
   title     = {The space distribution of quasars},
   journal   = annrev ,
   year      = {1990},
   volume    = {28},
   pages     = {437-489}
}


@article{Haw93.1,
   author    = {Hawkins, R. and V{\'e}ron, P.},
   title     = {The quasar luminosity function from a variability-selected sample},
   journal   = mnras,
   year      = {1993},
   volume    = {260},
   pages     = {202-208}
}


@inproceedings{Hjorth93.1,
   crossref  = {Liege93},
   author    = {Hjorth, J. and Jensen, F.G.},
   title     = {Nordic Optical Telescope imaging of the gravitational lens candiadate QSO1208+1011},
   booktitle = {Li{\'e}ge Conference on GL proceedings},
   year      = {1993},
   pages     = {103-108},
   journal   = {31'st Liege Int. Astroph. Coll.}
}


@article{Jaunsen94.1,
   author    = {Jaunsen, A.O.},
   title     = {Astronomical image enhancement by resampling, shifting, combination and deconvolution},
   journal   = { },
   year      = {1994},
   note      = {in preperation}
}


@article{Kassiola93.1,
   author    = {Kassiola, A. and Kovner, I.},
   title     = {Elliptical mass distributions versus elliptical potentials in gravitational lenses},
   journal   = apj,
   year      = {1993},
   volume    = {417},
   pages     = {450-473}
}


@article{Kjeldsen90,
   author    = {Kjeldsen, Hans},
   title     = {Test of the Stockholm CCD camera mounted on the NOT adaptor},
   journal   = {NOT News},
   year      = {1990},
   volume    = {2},
   number    = { }
}


@inproceedings{Kjeldsen92.1,
   author    = {Kjeldsen, H.},
   title     = {the inversion of digitial iamges in astronomy},
   booktitle = {Proceedings of the Interdisciplinary inversion workshop 1},
   organization = {GeoSkrifter 41, 117-122},
   year      = {1992},
   month     = {August},
   editor    = {Jackobsen, B.H.}
}


@article{Klimov63,
   author    = {Klimov, Y.G.},
   title     = { },
   journal   = {Sov. Phys. Doklady},
   year      = {1963},
   volume    = {8},
   pages     = {119}
}


@article{Kochanek87.1,
   author    = {Kochanek, C.S. and Blandford, R.D.},
   title     = {Gravitational imaging by isolated elliptical potential wells. II. Probability distributions},
   journal   = apj,
   year      = {1987},
   volume    = {321},
   pages     = {676}
}


@article{Kochanek91.1,
   author    = {Kochanek, C.S.},
   title     = { },
   journal   = apj,
   year      = {1991},
   volume    = {373},
   pages     = {354}
}


@article{Kochanek91.2,
   author    = {Kochanek, C.S.},
   title     = {Selection effects in optical surveys for gravitational lenses},
   journal   = apj,
   year      = {1991},
   month     = {October},
   volume    = {379},
   pages     = {517-531}
}


@article{Kochanek91.3,
   author    = {Kochanek, C.S.},
   title     = { },
   journal   = apj,
   year      = {1991},
   volume    = {382},
   pages     = {58}
}


@article{Kochanek93.1,
   author    = {Kochanek, C.S.},
   title     = {Analytic results for the gravitational lens statistics of SIS in general cosmologies},
   journal   = mnras,
   year      = {1993},
   volume    = {261},
   pages     = {453}
}


@article{Kochanek93.2,
   author    = {Kochanek, C.S.},
   title     = {The analysis of gravitational lens surveys. I. Selection functions and ambigous candidates},
   journal   = apj,
   year      = {1993},
   volume    = {417},
   pages     = {438-449}
}


@article{Kochanek93.3,
   author    = {Kochanek, C.S.},
   title     = {The analysis of gravitational lens surveys. II. Maximum likelihood models and singular properties},
   journal   = apj,
   year      = {1993},
   volume    = {419},
   pages     = {12-29}
}


@misc{Kochanek94.1,
   author    = {Kochanek, C.},
   year      = {1994},
   month     = {January},
   howpublished = {private communication},
   note      = { }
}


@article{LDSspes1,
   author    = {Thomsen, B.},
   title     = {The Aarhus-Tromso LDS},
   journal   = {NOT News},
   year      = {1990},
   volume    = {2},
   number    = { }
}


@article{LDSspes2,
   author    = {Jensen, F.G.},
   title     = {Status of the LDS},
   journal   = {NOT News},
   year      = {1992},
   volume    = {5},
   number    = { }
}


@article{Liebes64,
   author    = {Liebes, S.},
   title     = { },
   journal   = prb,
   year      = {1964},
   volume    = {133},
   pages     = {835}
}


@proceedings{Liege93,
   title     = {"Gravitational Lenses in the Universe": 31st Li{\`e}ge Int. Astroph. Coll.},
   organization = {Li{\`e}ge Conference},
   year      = {1993},
   month     = {June},
   editor    = {Surdej, J. and Fraipoint-Caro, D. Gosset, E. and Refsdal, S. and Remy, M.}
}


@article{Lucy74,
   key       = {Lucy 74},
   author    = {Lucy, Leon B.},
   title     = {An iterative technique for the rectification of observed distributions},
   journal   = {Astronomical J.},
   year      = {1974},
   volume    = {79},
   pages     = {745}
}


@book{MTW73,
   author    = {Misner, C.W. and Thorne, K.S. and Wheeler, J.A.},
   title     = {Gravitation},
   year      = {1973},
   publisher = {W.H. Freeman}
}


@article{Mag88.1,
   author    = {Magain, P. and Surdej, J. and Swings, J.-P. and Borgeest, U. and Kayser, R. and Kuhr, H. and Refsdal, S. and Remy, M.},
   title     = {Discovery of a quadruply lensed quaser: the 'clover leaf' H1413+117},
   journal   = nature,
   year      = {1988},
   month     = {July},
   volume    = {334},
   pages     = {325-327}
}


@article{Mag92.1,
   author    = {Magain, P. and Surdej, J. and Swings, J.-P. and Vanderriest, C. and Pirenne, B. and Hutsem{\'e}kers, D.},
   title     = {Q 1208+1011: the most distant multiply imaged quasar, or a binary?},
   journal   = aa,
   year      = {1992},
   volume    = {253},
   pages     = {L13-L16}
}


@article{Mao91,
   author    = {Mao, S.},
   title     = {Statistics of gravitational lenses: the uncertainties},
   journal   = apj,
   year      = {1991},
   volume    = {380},
   pages     = {9}
}


@article{Mao93.2,
   key       = {Mao93.2},
   author    = {Maoz,D. and Bahcall,J.N. and Schneider,D.P. and Bahcall, N.A. and Djorgovski,S. et al.},
   title     = {The HST snapshot survey. IV. A summary of the search for graviationally lensed quasars},
   journal   = apj,
   year      = {1993},
   volume    = {409},
   pages     = {28}
}


@article{Mao93.3,
   author    = {Maoz, D. and Rix, H.-W.},
   title     = {Early-type galaxies, dark halos, and gravitational lensing statistics},
   journal   = apj,
   year      = {1993},
   volume    = {416},
   pages     = {425-443}
}


@inproceedings{Nar93.1,
   crossref  = {Liege93},
   author    = {Narayan, R. and Wallington, S.},
   title     = {Magnification bias and gravitational lensing statstics},
   booktitle = {"Gravitational lenses in the universe"},
   year      = {1993}
}


@article{Narayan89.1,
   author    = {Narayan, R.},
   title     = {Gravitaional lensing and quasar-galaxy correlations},
   journal   = apj,
   year      = {1989},
   volume    = {339},
   pages     = {L53}
}


@article{Nemi91,
   author    = {Nemiroff, R.J.},
   title     = {On the probability of detection of a single gravitational lens},
   journal   = apj,
   year      = {1989},
   month     = {June},
   volume    = {341},
   pages     = {579-587}
}


@article{Nilsson93.1,
   author    = {Nilsson, K.},
   title     = {A new linearity test of the S-CCD camera},
   journal   = {NOT-News},
   year      = {1993},
   month     = {November},
   volume    = {7},
   pages     = {37}
}


@article{Phinney86.1,
   author    = {Phinney, E.S. and Blandford, R.D.},
   title     = { },
   journal   = nat,
   year      = {1986},
   volume    = {321},
   pages     = {569}
}


@article{PostGell84.1,
   author    = {Postman, M. and Geller, M.J.},
   title     = { },
   journal   = apj,
   year      = {1984},
   volume    = {281},
   pages     = {95}
}


@article{Pre73.1,
   author    = {Press, J.W. and Gunn, J.E.},
   title     = {Method for detecting a cosmological density of condensed objects},
   journal   = apj,
   year      = {1973},
   volume    = {185},
   pages     = {397}
}


@article{Ref94.1,
   author    = {Refsdal, S. and Surdej, J.},
   title     = {Gravitational Lenses},
   journal   = {Reports on Progress in Physics},
   year      = {1994},
   volume    = {57},
   number    = {2},
   pages     = {117}
}


@article{Refsdal64.1,
   author    = {Refsdal, S.},
   title     = {The gravitational lens effect},
   journal   = mnras,
   year      = {1964},
   volume    = {128},
   pages     = {295}
}


@article{Refsdal64.2,
   author    = {Refsdal, S.},
   title     = { },
   journal   = mnras,
   year      = {1964},
   volume    = {128},
   pages     = {307}
}


@inproceedings{Refsdal65.1,
   author    = {Refsdal, S.},
   title     = { },
   booktitle = {Proc. Intern. Conf. on Relativistic Theory of Gravitation},
   year      = {1965},
   journal   = {Proc. Intern. Conf. on Relativistic Theory of Gravitation}
}


@article{Refsdal66.1,
   author    = {Refsdal, S.},
   title     = {On the possibility of testing cosmological theories from the gravitational lens effect},
   journal   = mnras,
   year      = {1966},
   volume    = {132},
   pages     = {101}
}


@article{Refsdal70.1,
   author    = {Refsdal, S.},
   title     = { },
   journal   = apj,
   year      = {1970},
   volume    = {159},
   pages     = {357}
}


@article{Refsdal92,
   author    = {Refsdal, S. and Surdej, J.},
   title     = {Gravitational Lensing},
   journal   = {Highlights of Astronomy},
   year      = {1992},
   volume    = {9},
   pages     = {3-32}
}


@article{Refsdal93,
   author    = {Refsdal, S. and Stabell, R.},
   title     = {Gravitational microlensing variability caused by small masses},
   journal   = {Astronomy and Astrophysics},
   year      = {1993}
}


@article{Rich72,
   key       = {Richardson 72},
   author    = {Richardson},
   title     = {Bayesian probability},
   journal   = {Journal Optical Society of America},
   year      = {1972},
   volume    = {66},
   pages     = {55}
}


@book{Ruskai92,
   key       = {Ruskai92},
   title     = {Wavelets and their applications},
   year      = {1992},
   editor    = {M.B. Ruskai},
   publisher = {Boston: Jones and Bartlett},
   series    = {Jones and Bartlett books in mathematics},
   note      = {xiii, 474 s.}
}


@article{Sch76.1,
   author    = {Schechter, P.},
   title     = { },
   journal   = apj,
   year      = {1976},
   volume    = {203},
   pages     = {297}
}


@book{Sch92.1,
   author    = {Schneider, P. and Ehlers, J. and Falco, E.E.},
   title     = {Gravitational Lenses},
   year      = {1992},
   publisher = {Springer-Verlag}
}


@booklet{Stetson92,
   key       = {Stetson, DAOPHOTII Users Manual},
   author    = {Stetson, Peter B.},
   title     = {Users Manual for DAOPHOT II},
   year      = {1992},
   pages     = {68}
}


@article{Sur87.1,
   author    = {Surdej, J. and Magain, P. and Swings, J.P. and Borgeest, U. and Courvoisier, T.J.-L. and Kayser, R. and Kellermann, K.I. and K{\"u}hr, H. and Refsdal, S.},
   title     = {A new case of gravitational lensing},
   journal   = nature,
   year      = {1987},
   volume    = {329},
   pages     = {695}
}


@article{Sur88.1,
   author    = {Surdej, J. and Magain, P. and Swings, J.P. and Remy, M. and Borgeest, U. and Kayser, R. and Refsdal, S.},
   title     = {Search for gravitational lensing from a survey of higly luminous quasars},
   journal   = {ASP Conf. Ser.},
   year      = {1988},
   volume    = {2},
   pages     = {183}
}


@article{Sur88.2,
   author    = {Surdej, J. and Magain, P. and Swings, J.P. and Borgeest, U. and Courvoisier, T.J.-L. and Kayser, R. and Kellermann, K.I. and K{\"u}hr, H. and Refsdal, S.},
   title     = {Observations of the new gravitational lens system UM 673=Q 0142-100},
   journal   = aa,
   year      = {1988},
   volume    = {198},
   pages     = {49-60}
}


@article{Sur93.1,
   key       = {SCC+},
   author    = {Surdej, J. and Claeskens, J.F. and Crampton, F. and Filippenko, A.V. and Hutsem{\'e}kers, D.},
   title     = {Gravitational lensing statistics based on a large sample of higly luminous quasars},
   journal   = aj,
   year      = {1993},
   volume    = {105},
   pages     = {2064}
}


@misc{Surdej94,
   author    = {Surdej, J.},
   year      = {1994},
   howpublished = {private communication},
   note      = { }
}


@article{TOG,
   key       = {TOG},
   author    = {Turner, E.L. and Ostriker, J.P. and Gott, J.R.},
   title     = {The statistics of gravitational lenses: the distributions of image angular separations and lens redshifts},
   journal   = apj,
   year      = {1984},
   month     = {September},
   volume    = {284},
   pages     = {1-22},
   note      = {(TOG)}
}


@book{Teuber89,
   key       = {Teuber J., Digital Billedbehandling},
   author    = {Teuber, Jan},
   title     = {Digital Billedbehandling},
   year      = {1989},
   publisher = {Teknisk Forlag A/S}
}


@article{Teuber94.1,
   author    = {Teuber, J. and Ostensen, R. and Stabell, R. and Florentin-Nielsen, R.},
   title     = {Rotate and stare: A new method for PSF estimation},
   journal   = mnras,
   year      = {1994},
   note      = {submitted}
}


@article{Tul77.1,
   author    = {Tully, R. B. and Fisher, J.R.},
   title     = { },
   journal   = aa,
   year      = {1977},
   volume    = {54},
   pages     = {661}
}


@article{Tyson88.1,
   author    = {Tyson, J.A.},
   title     = { },
   journal   = aj,
   year      = {1988},
   volume    = {96},
   pages     = {1}
}


@inproceedings{Van93.1,
   author    = {Van Drom, E. and Surdej, J. and Magain, P. and Hutsem{\'e}kers, D. and Gosset, E. and Claeskens J.F. and Shaver, P. and Melnick, J.},
   title     = {Galaxies statistics around Highly Luminous Quasars: the ESO sample},
   booktitle = {"Gravitational Lenses in the Universe"},
   organization = {31st Li{\`e}ge Int. Astrophysical Coll.},
   year      = {1993},
   journal   = {31st Li{\`e}ge}
}


@booklet{Veron91.1,
   author    = {V{\'e}ron-Cetty, M.-P. and V{\'e}ron, P.},
   title     = {A Catalogue of Quasars and Active Nuclei},
   year      = {1991},
   howpublished = {ESO Report nr.13}
}


@article{Wal79.1,
   author    = {Walsh, D. and Carswell, R.F. and Weymann, R.J.},
   title     = {0957+561 A,B: twin quasistellar objects or gravitional lens ?},
   journal   = nature,
   year      = {1979},
   volume    = {279},
   pages     = {381}
}


@article{Wallington93.1,
   author    = {Wallington, S. and Narayan, R.},
   title     = {The influence of core radius on gravitational lensing by elliptical lenses},
   journal   = apj,
   year      = {1993},
   volume    = {403},
   pages     = {517-529}
}


@book{Wein72.1,
   author    = {Weinberg, S.},
   title     = {Gravtation and cosmology: principles and applications of the general theory of relativity},
   year      = {1972},
   editor    = {MIT},
   publisher = {Wiley & Sons, Inc.}
}


@article{Wills,
   author    = {Wills, B.J. and Wills, D.},
   title     = {Spectroscopy of 125 QSO candidates and radio galaxies},
   journal   = apjss,
   year      = {1979},
   month     = {December},
   volume    = {41},
   pages     = {689-700}
}


@article{Wu93.1,
   author    = {Wu, X.P.},
   title     = {Velocity dispersions in statistical lensing},
   journal   = apj,
   year      = {1993},
   volume    = {411},
   pages     = {513}
}


@article{Yee93.1,
   author    = {Yee, H. and Filippenko, A. and Tang, D.},
   title     = {A high-resolution gravitational lens survey},
   journal   = aj,
   year      = {1993},
   volume    = {105},
   number    = {1},
   pages     = {7-16}
}


@article{Zel64.1,
   author    = {Zel'dovich, Ya.B.},
   title     = { },
   journal   = {Soviet Astronomy},
   year      = {1964},
   volume    = {8},
   pages     = {13}
}


@article{Zwi37.1,
   author    = {Zwicky, F.},
   title     = {On the probability of detecting nebulae which act as gravitational lenses},
   journal   = prl,
   year      = {1937},
   volume    = {51},
   pages     = {679}
}


@article{Zwi37.2,
   author    = {Zwicky, F.},
   title     = {Nebulae as gravitational lenses},
   journal   = prl,
   year      = {1937},
   volume    = {51},
   pages     = {290}
}