Não informado. (1913). Extension Bulletin. Washington State University, Cooperative Extension Service.
Chicago-referens (17:e uppl.)Não informado. Extension Bulletin. Pullman, Wash: Washington State University, Cooperative Extension Service, 1913.
MLA-referens (8:e uppl.)Não informado. Extension Bulletin. Washington State University, Cooperative Extension Service, 1913.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.