MacCorkle, Stuart A.
D.C. Heath and Company, 1948
Buku Teks
Tennet, Irwing
Englewood Cliffs, N.J., Prentice-Hall
Buku Teks
Kamer, Pearl M., author
Frederick A. Praeger, 1983
Buku Teks
Abdurrahman, author
Fakultas Ekonomi dan Bisnis Universitas Indonesia, 2013
UI - Skripsi (Membership)
Webster, Donald H., author
Harper & Row , 1958
Buku Teks