Consequences of the validity of Huygens' principle for the conformally invariant scalar wave equation, Weyl's neutrino equation and Maxwell's equations on Petrov type II space-times
J. Carminati, S. R. Czapor, R. G. McLenaghan, G. C. Williams (1991)
Annales de l'I.H.P. Physique théorique
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