Giannoni, Fabio; Lombardi, Marco Gravitational lenses: odd or even images? (English) Zbl 0942.83009 Classical Quantum Gravity 16, No. 6, 1689-1694 (1999). Cited in 3 Documents MSC: 83B05 Observational and experimental questions in relativity and gravitational theory 58E05 Abstract critical point theory (Morse theory, Lyusternik-Shnirel’man theory, etc.) in infinite-dimensional spaces 83C10 Equations of motion in general relativity and gravitational theory Keywords:light rays in vacuum space-times; Morse relations; gravitational lens effect; thin lens model; Einstein cross PDF BibTeX XML Cite \textit{F. Giannoni} and \textit{M. Lombardi}, Classical Quantum Gravity 16, No. 6, 1689--1694 (1999; Zbl 0942.83009) Full Text: DOI