Perum Percetakan Uang Republik Indonesia, [date of publication not identified]
Buku Referensi
Perum Percetakan Uang Republik Indonesia, [date of publication not identified]
Buku Referensi
The Reader's Digest Association
The Reader`s Digest Association, 1967
Buku Teks SO
Frans M. Parera
Kompas Media Nusantara, 2000
Buku Teks SO
Irza Arnyta Djafaar
Universitas Indonesia, 1999
UI - Tesis Membership