Time minimizing trajectories in Lorentzian geometry the general-relativistic brachistochrone problem
Fabio Giannoni Volker Perlick; Piccione, Paolo; Verderesi, José Antonio
São Paulo IME-USP 1998
Available at IME - Inst. Matemática e Estatística (IME-RT-M QA336.RT I591 1998 v.28 e.1 ) and other locations(GetIt)