Buku Referensi
British Media Publications, 1989
Buku Referensi
Thomas Skinner Directories, 1986
Buku Referensi
Alexander Kohar, author
Fakultas Teknik Universitas Indonesia, 2002
UI - Skripsi (Membership)
Cohen, Bernard Cecil, 1926-, author
Princeton University Press, 1969
Buku Teks