Singer, Francis J., and Bruce B. Ackerman. Food Availability, Reproduction, and Conditions of European Wild Boar in Great Smoky Mountains National Park In Research/Resources Management Report. Gatlinburg, TN: Uplands Field Research Laboratory, 1981.

Howe, Thomas D., Francis J. Singer, and Bruce B. Ackerman. "Forage Relationships of European Wild Boar Invading Northern Hardwood Forest." Journal of Wildlife Management 45, no. 3 (1981): 748-754.

Ackerman, Bruce B., Mark E. Harmon, and Francis J. Singer. Studies of European Wild Boar in the Great Smoky Mountains National Park, Part II: Seasonal Food Habits In Report to the Superintendent. U. S. Department of the Interior, National Park Service, Southeast Regional Office, 1978.

Ackerman, Bruce B., Mark E. Harmon, and Francis J. Singer. Studies of the European Wild Boar in the Great Smoky Mountains National Park, Part II, Seasonal Food Habits In First Annual Report, Part II to the Superintendent. Gatlinburg, TN: U.S. Department of the Interior, National Park Service, Southeast Regional Office, 1978.