Gale, Esson M.
Michigan State College Press, 1953
Buku Teks
Rossabi, Morris, author
Wiley Balckwell, 2014
Buku Teks
Roberts, J. A. G. (John Anthony George), 1935-, author
Palgrave Macmillan, 2011
Buku Teks
Lord, Gabrielle, author
McPhee Gribble, 1990
Buku Teks
Latourette, Kenneth Scott, author
Penguin Books, 1954
Buku Teks