Butterfield, Herbert
The Free Press , 1957
Buku Teks
Partridge, Eric, 1894-1979, author
Routledge, 1991
Buku Referensi
edited by Jean-Jacques Hublin, Shannon P. McPherron
Springer Science, 2012
eBooks
Biswas, B. N.
Oxford & IBH Publishing Co., 1988
Buku Teks
Smith, Preserved, author
Collier Books, 1962
Buku Teks