Babbage, Ross, 1949-
Allen & Unwin, 1990
Buku Teks
International Bank for Reconstruction and Development
World Bank, 1994
Buku Teks
Evi Fitriani
2018
UI - Makalah dan Kertas Kerja
edited by Patrick Troy
Cambridge University Press, 1995
Buku Teks SO
Buku Teks