Lambert, Clark
John Wiley & Sons, 1981
Buku Teks
Allen, Peter, author
Pitman, 1998
Buku Teks
Wingate, John W., author
South-Western Publishing, 1959
Buku Teks
Allen, Robert Y., author
McGraw-Hill, 1984
Buku Teks
Sutton, Kelso, author
McGraw-Hill, 1949
Buku Teks