United Nations Development Programme, 1980
Buku Teks
resources for the future, 1981
Buku Teks
National Academy of Sciences , 1976
Buku Teks
Siti Rahmawati, author
Fakultas Ilmu Komputer Universitas Indonesia, 2017
UI - Tugas Akhir
Esman, Milton J., author
Cornell University Press, 1984
Buku Teks