MacDonald, Austin F.
Thomas Y. Crowell , 1951
Buku Teks
MacCorkle, Stuart A.
D.C. Heath and Company, 1948
Buku Teks
Anderson, William, 1888-
Holt , 1954
Buku Teks
OConnor, Karen
Addison Wesley Longman, 2001
Buku Teks
Sayre, Wallace S.
Barnes & Noble, 1964
Buku Teks