U.S. Departement of Agriculture. Forest Service, 993
Buku Teks
International Engineering Consortium
National Engineering Consortium., 1992
eBooks
Europa Publication Limited, 1994
Buku Referensi
Wanda Katili, author
Fakultas Ekonomi dan Bisnis Universitas Indonesia, 1983
UI - Skripsi Membership
Hawthorne, Nathaniel, author
Narasi, 2004
Buku Teks