Não informado. (1919). Department circular. U.S. Department of Agriculture.
Chicago-Zitierstil (17. Ausg.)Não informado. Department Circular. Washington: U.S. Department of Agriculture, 1919.
MLA-Zitierstil (8. Ausg.)Não informado. Department Circular. U.S. Department of Agriculture, 1919.
Achtung: Diese Zitate sind unter Umständen nicht zu 100% korrekt.