Bursk, Edward Collins, author
Cambridge, Mass, Harvard University Press
Buku Teks
Vandenburgh III, Edward C.
The Bobbs-Merill Company,Inc., 1968
Buku Teks
Basic Book, 1968
Buku Teks
Hirst, David L., author
Macmillan, 1985
Buku Teks
West Publishing Co., 1996
Buku Teks