- Cottrell, C. B., J. C. Holms, and D. A. Ross. 1965. Spruce beetle report, Prince George Forest District, 1964. Canada Department of Forestry, Forest Entomology Laboratory, Vernon, British Columbia, Information Report 1964. 6 p.
- Cottrell, C. B., J. C. Holms, and D. A. Ross. 1966a. Status of the spruce beetle, Prince George Forest District, 1965. Pages 187-196 in Annual district reports. Forest Insect and Disease Survey, 1965. Canada Department of Forestry, Forest Research Laboratory, Victoria, British Columbia, Internal Report BC-4.
- Cottrell, C. B., J. C. Holms, and D. A. Ross. 1966b. Status of the spruce beetle, Prince George Forest District, 1965. Canada Department of the Environment, Canadian Forestry Service, Forest Research Laboratory, Victoria, British Columbia, Information Report BC-X-3. 4 p.