Tozer, E.T. The Trias and its ammonoids: the evolution of a time scale - Ontario Geological Survey of Canada 1984 - 171 p. ilus. - Miscellaneous Report n.35 . Subjects--Topical Terms: AMMONOIDEAPALEONTOLOGÍATRIASICO Subjects--Geographic Terms: CANADA Universal Decimal Class. No.: 551.763/T77