Routledge and Kegan Paul, 1958
Buku Teks
University Tutorial Press , 1977
Buku Teks
edited by T.V. Smith and Marjorie Grene
University of Chicago Press, 1957
Buku Teks
Gouda Quint, 1981
Buku Teks
Robert Maynard Hutchins, editor in chief
Encyclopaedia Britannica, Inc., 1952
Buku Referensi