Crawfurd, John
Oxford University Press, 1971
Buku Referensi
edited by Christopher T.H. Baker, Geoffrey F. Miller
Academic Press, 1982
Buku Teks SO
Freddrich Ebert Stiftung , 1971
Buku Teks SO
The Institute of Asian Research, 1996
Buku Teks SO
Mohammad Hatta, 1902-1980
Cornell University Press, 1957
Buku Teks