Troxell, Mary D., author
Gregg Division McGraw-Hill Book Company, 1981
Buku Teks
Andrea Rahardiana Putri, author
Fakultas Ekonomi dan Bisnis Universitas Indonesia, 2017
UI - Skripsi (Membership)
edited by Martin M. Pegler
Retail Reporting Corporation, 1989
Buku Referensi
Wingate, John W., author
Prentice-Hall, 1957
Buku Teks
Rosenberg, Jerry M., author
John Wiley & Sons, 1995
Buku Referensi