I would like to acknowledge useful discussions and correspondences with Jean Quashnock and Cole Miller on gravitational lensing, John Carlstrom on galaxy clusters, and Heinz Andernach, André Fletcher, Frazer Owen and Ian Smail on gravitational lensing of radio sources due to foreground clusters and the possibility of an observational search to find such sources. I would also like to thank the referees for their prompt refereeing of the three separate papers on optical, radio, sub-mm lensed sources, as well as the combined version. I have greatly benefitted from their detailed comments and valuable advice from Peter Schneider, which led to a significant improvement in this paper. This study was partially supported by the McCormick Fellowship at the University of Chicago, and a Grant-In-Aid of Research from the National Academy of Sciences, awarded through Sigma Xi, the Scientific Research Society.
© European Southern Observatory (ESO) 1999
Online publication: December 16, 1998