J. M. V. Coutinho e J. Hachiro, “ Distribution, mineralogy, petrography, provenance and significance of Permian ash-carrying deposits in the Paraná Basin ”, Geol. USP. Sér. Cient., vol. 5, nº 1, p. 29–39, jun. 2005, doi: 10.5327/S1519-874X2005000100003.