Ticehurst, George William, author
Longman, 2000
Buku Teks
Richard J. Semenik, Thomas C. O'Guinn, Chris Allen, Hans Kaufmann
Wadsworth and Cengage Learning, 2012
Buku Teks
Greer, Charles R., author
Prentice-Hall, 2001
Buku Teks
McCarthy, E. Jerome, author
Irwin , 1978
Buku Teks
McCarthy, E. Jerome, author
Irwin , 1975
Buku Teks