Arnold, Alvin L.
Warren, Gorham & Lamnont, 1981
Buku Teks
Wurtzebach, Charles H.
John Wiley & Sons, 1995
Buku Teks
Amalia Hanifah, author
Universitas Indonesia, 2004
UI - Tesis Membership
Artikel Jurnal
Shenkel, William M., author
Business Publications , 1980
Buku Teks