Milton-Edwards, Beverly
Routledge, 2014
Buku Teks
Williamson, James A., author
Macmilan and Co,, 1950
Buku Teks
Andrews, George E., author
Springer, 2012
eBooks
Nourse, Alan E.
Time Incorporated, 1964
Buku Referensi
Nahavandi, Firouzeh, author
Palgrave Macmillan, 2016
Buku Teks