editor, Terrell Croft [and others]
McGraw-Hill, 1981
Buku Referensi
Radin, Max
St Paul Minn, 1936
Buku Teks
Whitford, Harold C.
Regents Publishing, 1973
Buku Teks
edited by Gary Hoover, Alta Campbell, Patrick Spain
The Reference Press, 1991
Buku Referensi
Hawes, Gene R., author
American University Press, 1967
Buku Teks