Tiger Books International, 1994
Buku Referensi
Katzner, Kenneth, author
John Wiley & Sons, 1994
Buku Referensi
Black, Henry Campbell, author
West Publishing, 1990
Buku Referensi
Eckersley, C. E. (Charles Ewart), 1892-1967, author
Longmans, Green and Co., 1953
Buku Referensi
HarperCollins, 2011
Buku Referensi