1. Axelrod D.I. (1959) Late Cenozoic evolution of the Sierran Bigtree forest. Evol. 13: 9–28.
2. Barthel M. (1976) Farne und Cycadeen. Eozäne Floren des Geiseltales. Abh. Zentr. Geol Inst. 26: 439–498.
3. Boulter M.C. and Kvaiek Z. (1989) The Palaeocene flora of the Isle of Mull. Spec. Pap. Palaeontol. 42: 11–49.
4. Chaney R.W. (1936) The succession and distribution of Cenozoic floras around the northern Pacific basin. In: T.H. Goodspeed (ed.) Essays in Geobotany in honour of William Albert Setchell: 55–85. Univiversity California Press, Berkeley.
5. Chaney R.W. (1959) Miocene floras of the Columbia Plateau, F. Composition and interpretation. Carnegie Institute Washington Publications 617: 11–34.