Não informado. (1966). Resource Bulletin NC. North Central Forest Experiment Station, Forest Service.
Chicago-referens (17:e uppl.)Não informado. Resource Bulletin NC. Saint Paul, Minn: North Central Forest Experiment Station, Forest Service, 1966.
MLA-referens (8:e uppl.)Não informado. Resource Bulletin NC. North Central Forest Experiment Station, Forest Service, 1966.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.