The Atlantic Monthly Company, 1996
Majalah, Jurnal, Buletin
Herter, Christian A., author
Harper & Row, 1963
Buku Teks
Chapin, Miriam
The Ryerson Press , 1956
Buku Teks
Huntley, James R., author
NATO Information Service, 1972
Buku Teks
Gardner, Richard K., author
Oxford University Press, 2015
Buku Teks