Hartley, W. H., & Vincent, W. S. (1970). American civics (3rd ed.). Harcourt brace jovanovich.
Dyfyniad Arddull ChicagoHartley, William H., and William S. Vincent. American Civics. 3rd ed. New York: Harcourt brace jovanovich, 1970.
Dyfyniad MLAHartley, William H., and William S. Vincent. American Civics. 3rd ed. Harcourt brace jovanovich, 1970.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.