BKPM, 1991
Buku Teks SO
ASEAN Secretariat, 1999
eBooks
Fatouros, A.A.
Columbia University Press, 1962
Buku Teks SO
by The Central Bank of Indonesia (Bank Negara Indonesia Unit I)
The Central Bank of Indonesia (Bank Negara Indonesia Unit I), 1962
Buku Teks SO
Medhurst, David
Blackwell Scientific Publications, 1994
Buku Referensi