Beckmann, Jean-Pierre; Bolli, Hans M.; Perch-Nielsen, Katharina; Proto Decima, Franca; Saunders, John B.; Toumarkine, Monique (1981): Major calcareous nannofossil and foraminiferal events between the middle Eocene and early Miocene. Elsevier, Amsterdam, Netherlands, In: Pomerol, Charles, Paleogene paleogeography and the geological events of the Eocene/Oligocene boundary; Proceedings of the symposium on Paleogene biostratigraphy and paleogeography, 36 (3-4), 155-190, georefid:1983-047233