Overman, Michael
Lutterworth Press, 1974
Buku Teks
Allen, John
Nelson, 1990
Buku Teks
Pehrsson, Anders, author
Routledge, 1996
Buku Teks
Springer Singapore, 2019
eBooks
Agus Susilowarno, author
Fakultas Eknonomi dan Bisnis Universitas Indonesia, 2011
UI - Tesis Open