Europe Publications Limited, 1984
Buku Referensi
Conrad, Earl
New York, 1961
Buku Teks
edited by Anna Rothe
The H.W. Wilson Company, 1953
Buku Teks SO
Perum Percetakan Uang Republik Indonesia, [Date of publication not identified]
Buku Referensi
Law, Stephen
Quersus, 2013
Buku Teks SO