Neumayer, Eric
Cambridge University Press, 2017
eBooks
Armitage, P.
Blackwell Scientific Publication, 1985
Buku Teks SO
Osborn, John F.
Blackwell, 1979
Buku Teks SO
Fisher, Ronald A.
Hafner Press, 1970
Buku Teks SO
Myers, Jerome L.
Routledge, 2010
Buku Teks SO