References:

Burnett, J. A. (1998). Upper Cretaceous. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series. 132-199. gs

Perez-Rodriguez, I., Lees, J. A., Larasoaña, J. C., Arz, J. A. & Arenillas, I. (2012). Planktonic foraminiferal and calcareous nannofossil biostratigraphy and magnetostratigraphy of the uppermost Campanian and Maastrichtian at Zumaia, northern Spain. Cretaceous Research. 37: 100-126. gs

Roth, P. H. (1978). Cretaceous nannoplankton biostratigraphy and oceanography of the northwestern Atlantic Ocean. Initial Reports of the Deep Sea Drilling Project. 44: 731-760. gs

Wind, F. H. & Wise, S. W. (1983). Correlation of upper Campanian-lower Maestrichtian calcareous nannofossil assemblages in drill and piston cores from the Falkland Plateau, southwest Atlantic Ocean. Initial Reports of the Deep Sea Drilling Project. 71: 551-563. gs