Brush, W. D., Butcher , D., & Collingwood, G. (1974). Knowing your trees (Rev. ed.). The American Forestry Association.

Brush, Warren D., Devereux Butcher , and G.H Collingwood. Knowing Your Trees. Rev. ed. Washington, D.C.: The American Forestry Association, 1974.

Brush, Warren D., et al. Knowing Your Trees. Rev. ed. The American Forestry Association, 1974.