Fossati, Diego, author
ISEAS Publishing, 2017
eBooks
edited by Paul Boreham, Geoffrey Stokes and Richard Hall
Pearson-Longman, 2004
Buku Teks
Schuman, Frederick L., author
McGraw-Hill, 1969
Buku Teks
Bull, Hedley, author
Macmillan, 1995
Buku Teks
Kitzinger, Uwe W., author
Frederick A. Praeger, 1963
Buku Teks