Não informado. (2020). Progress Report. Pennsylvania State University, Agricultural Experiment Station.
Chicago-referens (17:e uppl.)Não informado. Progress Report. University Park, Pa: Pennsylvania State University, Agricultural Experiment Station, 2020.
MLA-referens (8:e uppl.)Não informado. Progress Report. Pennsylvania State University, Agricultural Experiment Station, 2020.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.