Não informado. (1923). Minnesota Studies in Plant Science. University of Minnesota.
Chicago-referens (17:e uppl.)Não informado. Minnesota Studies in Plant Science. Minneapolis, Minn: University of Minnesota, 1923.
MLA-referens (8:e uppl.)Não informado. Minnesota Studies in Plant Science. University of Minnesota, 1923.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.