Меловой период

Núñez-Useche F., Moreno-Bedmar J.A., Company M., Barragán R. (2014) A negative carbon isotope excursion within the Dufrenoyia furcata Zone: proposal for a new episode for chemo-stratigraphic correlation in the Aptian // Carnets de Géologie [Notebooks on Geology], Brest, vol. 14, nº 6, p. 129-137.

http://paleopolis.rediris.es/cg/1406/index.html