Eugene R. Wittkopf, James M. McCormick, editor
Rowman & Littlefield publisher INC, 2008
Buku Teks
McCormick, James M., author
Thomson, 2005
Buku Teks
Langdon, Robert M., author
Littlefield Adams, 1961
Buku Teks
Herrick, Christopher, author
Longman, 2003
Buku Teks
edited by Ernest R. May
George-Braziller, 1963
Buku Teks