Gravitational lensing statistics with extragalactic surveys - II. Analysis of the Jodrell Bank-VLA Astrometric SurveyP. Helbig, D. Marlow, R. Quast, P. N. Wilkinson, I. W.A. Browne and L. V.E. KoopmansAstron. Astrophys. Suppl. Ser., 136 2 (1999) 297-305DOI: https://doi.org/10.1051/aas:1999467