Omar, Ogenyi
Financial times, 1999
Buku Teks
Dyonisius Beti
1990
UI - Tesis (Membership)
Taller, Terry
McGraw-Hill Ryerson, 1977
Buku Teks
Fakultas Ekonomi dan Bisnis Universitas Indonesia, 1990
UI - Skripsi (Membership)
Jones, Fred M.
Richard D. Irwin , 1957
Buku Teks