2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/35919It is shown that there are three vacuum and one electrovacuum solutions of diagonal plane waves with M=0 and constant Maxwell scalars. Namely, these are the single wave, Stoyanov, Babala and Bell-Szekeres solutions. A comparison is made with the planar solutions of Taub.6 pages, LaTeXGeneral Relativity and Quantum Cosmologytext