Significance of δDkerogen, δ13Ckerogen and δ34Spyrite from several Permian/Triassic (P/Tr) sections. - Nabbefeld, Birgit; Grice, Kliti; Schimmelmann, A.; Sauer, P.; Bottcher, M.; Twitchett, R. (Elsevier Science BV, 2010)