M. Wagreich, T. Küchler, & H. Summesberger. (2003). Correlation of calcareous nannofossil zones to the local first occurrence of Pachydiscus neubergicus (von Hauer, 1858) (Ammonoidea) in European Upper Cretaceous sections. Netherlands Journal of Geosciences, 82, 283-288. https://doi.org/10.1017/S0016774600020874