DeVore, M. L.; Pigg, K. B. (2007). "A brief review of the fossil history of the family Rosaceae with a focus on the Eocene Okanogan Highlands of eastern Washington State, USA, and British Columbia, Canada". Plant Systematics and Evolution. 266 (1–2): 45–57. doi:10.1007/s00606-007-0540-3. S2CID10169419.
Champigny, N.; Henderson, C. M.; Rouse, G. E. (1981). "New evidence for the age of the Skonun Formation, Queen Charlotte Islands, British Columbia". Canadian Journal of Earth Sciences. 18 (12): 1900–1903. Bibcode:1981CaJES..18.1900C. doi:10.1139/e81-176.
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Champigny, N.; Henderson, C. M.; Rouse, G. E. (1981). "New evidence for the age of the Skonun Formation, Queen Charlotte Islands, British Columbia". Canadian Journal of Earth Sciences. 18 (12): 1900–1903. Bibcode:1981CaJES..18.1900C. doi:10.1139/e81-176.
DeVore, M. L.; Pigg, K. B. (2007). "A brief review of the fossil history of the family Rosaceae with a focus on the Eocene Okanogan Highlands of eastern Washington State, USA, and British Columbia, Canada". Plant Systematics and Evolution. 266 (1–2): 45–57. doi:10.1007/s00606-007-0540-3. S2CID10169419.