Bartolo, R., Germinario, A. and Sanchez, M. (2004) “Orthogonal trajectories on stationary spacetimes under intrinsic assumptions”, Topological Methods in Nonlinear Analysis, 24(2), pp. 239–268. Available at: https://apcz.umk.pl/TMNA/article/view/TMNA.2004.027 (Accessed: 22 July 2024).