Racial variation in ponderosa pine,
A.E. Squillace [and] Roy R. Silen.

APA Citation

Squillace, A. E. (Anthony E.)., Silen, R. R. (1962). Racial variation in ponderosa pine. [Washington]: Society of American Foresters.

MLA Citation

Squillace, A. E. (Anthony E.), and Roy R Silen. Racial Variation In Ponderosa Pine. [Washington]: Society of American Foresters, 1962.

Warning: These citations may not always be complete (especially for serials).