Hoan, Daniel W.
Harcourt, Brace and Company, 1936
Buku Teks
MacDonald, Austin F., author
Thomas Y. Crowell , 1951
Buku Teks
Agger, Robert E.
N.Y. John-Wiley , 1966
Buku Teks
Lancaster, Lane W.
Van Nostrand , 1952
Buku Teks
Adrian, Charles R., author
McGraw-Hill, 1977
Buku Teks