ISAACSON, Peter, Jindřich HLADIL, Wei SHEN JIAN,
Jiří KALVODA and George GRADER. Late Devonian-Early Carboniferous glacial sediments of South America and sea-level drops on other continents.
Abh. Geol. B.-A. Wien, 1999, vol. 54, No 1, p. 239-256. ISSN 0016-7800.