Toynbee, Arnold J.
Beacon Press, 1961
Buku Teks SO
Schwab, Klaus, 1938-
Currency, 2017
Buku Teks
Flinn, M.W.
Longman, 1969
Buku Teks SO
Barker, Hannah
Oxford University Press, 2017
eBooks
Elena G Popkova, Yulia V Ragulina, Aleksei V Bogoviz
Springer, 2019
Buku Teks SO