Trajectories connecting two submanifolds on a non-complete Lorentzian manifold. Bartolo, Rossella, Germinario, Anna, Sánchez, Miguel (2004) Electronic Journal of Differential Equations (EJDE) [electronic only]
Twistors and gauge fields. Sergeev, A.G. (1986) International Journal of Mathematics and Mathematical Sciences
Two-body relativistic systems in external field Philippe Droz-Vincent (1989) Annales de l'I.H.P. Physique théorique