Spotte, Stephen
John Wiley & Sons, 1973
Buku Teks SO
Moller, H.
Verlag Moller-Kiel, 1983
Buku Teks
edited by A. Houghton Brodrick
Frederick A. Praeger, 1972
Buku Teks SO
Downer, John
Sterling Pub. Co., 1999
Buku Referensi
edited by Peter Messent and Donald Broom
Grolier International, 1993
Buku Referensi