De Wulf, Maurice
Dover Publications, Inc., 1922
Buku Teks
Gyula Klima, Fritz Allhoff, Anand Vaidya
BlackWell Publishing, 2007
Buku Teks
Russel, Bertrand, author
Routledge, 1948
Buku Teks
De Wulf, Maurice
Dover Publications , 1956
Buku Teks
McIlwain, Charles Howard, author
Macmillan, 1957
Buku Teks