TY - BOOK AU - Petters,Arlie O. ED - Levine,Harold ED - Wambsganss,J. TI - Singularity theory and gravitational lensing T2 - Progress in mathematical physics;no.21 U1 - 522.6 PY - 2001/// CY - Boston PB - Birkhauser KW - Gravitational lenses-mathematics KW - Singularities (mathematics) ER -