Manchester, S.; Pigg, K. (2008). "The Eocene mystery flower of McAbee, British Columbia". Botany. 86: 1034–1038. doi:10.1139/B08-044.
Pigg, K. B.; Dillhoff, R. M.; Devore, M. L.; Wehr, W. C. (2007). "New Diversity among the Trochodendraceae from the Early/Middle Eocene Okanogan Highlands of British Columbia, Canada, and Northeastern Washington State, United States". International Journal of Plant Sciences. 168 (4): 521. doi:10.1086/512104.