Keegan, William F.
Oxford University Press, 2017
eBooks
Angle, Paul M.
Rand McNally , 1958
Buku Teks
Hubbard, L. Ron, 1911-1986
Bridge Publications, Inc., 2012
Buku Referensi
Defoe, Daniel
Noble and Noble, 1959
Buku Teks
Stanford, D
London Longmans 1954
Buku Teks