Whitten, Kenneth W., author
Saunders College, 1992
Buku Teks
Umland, Jean B., author
Brooks/Cole, 1999
Buku Teks
Paul, Martin A., author
Harcourt, Brace & World, 1967
Buku Teks
Russell, John B., author
McGraw-Hill, 1981
Buku Teks
Umland, Jean B., author
St. Paul West, 1993
Buku Teks