Não informado. (1963). US Forest Service Research Paper PSW. U.S. Forest Service.
Chicago-viite (17. p.)Não informado. US Forest Service Research Paper PSW. Berkeley, Calif: U.S. Forest Service, 1963.
MLA-viite (8. p.)Não informado. US Forest Service Research Paper PSW. U.S. Forest Service, 1963.
Varoitus: Nämä viitteet eivät aina ole täysin luotettavia.