Livingstone, James M.
Macmillan, 1977
Buku Teks
Smith, Joan Macfarlance
Routledge & K. Paul, 1972
Buku Teks
Boyd, Harper W., Jr., author
Richard D. Irwin, 1977
Buku Teks
Sabine Hader, Michael Hader, Mike Kuhne, editors
[Springer, Springer], 2012
eBooks
Irma Hastarika, author
Fakultas Eknonomi dan Bisnis Universitas Indonesia, 2009
UI - Tesis (Open)