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
Rubin, Irwin M., author
McGraw-Hill, 1977
Buku Teks
Kelly, Alfred H.
W.W Norton & Company Inc., c 19
Buku Teks