1. Jurassic to Paleogene: Part 2: Paleogene geochronology and chronostratigraphy Berggren, William A.; Kent, Dennis V.; Flynn, John J. 1985 Articles GeophysicsPaleontology
2. The Neogene: Part 2: Neogene geochronology and chronostratigraphy Berggren, William A.; Kent, Dennis V.; Van Couvering, John A. 1985 Articles GeophysicsPaleontology