Cantor, Nathaniel, author
Harper & Brothers, 1958
Buku Teks
World Executive's Digest, 1981
Buku Teks
Scott, John, author
Spere British Institute of Management, 1984
Buku Teks
editor Wei Xiao
Shenyang Chubanche, 2002
Buku Referensi
Bernard, Chester I., author
Harvard University Press , 1966
Buku Teks