Benjafield, John G.
Allyn and Bacon , 1994
Buku Teks
Shaughnessy, John J., author
McGraw-Hill, 2006
Buku Teks
Langdridge, Darren, author
Pearson, 2004
Buku Teks
Kerlinger, Fred N. (Fred Nichols), 1910-, author
CBS College Publishing, 1986
Buku Teks
Kerlinger, Fred N. (Fred Nichols), 1910-, author
Harcourt Brace College Publishers, 1973
Buku Teks