Thomas Hegghammer, editor
Cambridge University Press, 2017
Buku Teks SO
Riggs, James L.
McGraw-Hill, 1974
Buku Teks
Trecker, Harleigh B.
Association Press, 1967
Buku Teks
edited by Wolfgang G. Weber, Michael Thomas, Annette Ostendorf and Lynne Chisholm
Springer, 2012
eBooks
Hauser, Arnold
Alfred A. Knopf , 1952
Buku Teks SO