Hugh L.Evans M.A.
Sweet and Maxwell, 1997
Buku Teks
Cooper, Robert U., author
Macmillan, 1953
Buku Teks
Cooper, Robert U., author
Macmillan, 1952
Buku Teks
Kastantin, Joseph T., author
Quorum Books, 1988
Buku Teks
Joseph, William, author
McGraw-Hill, 1983
Buku Teks