editor, James A. Gould
Charles E. Merrill , 1971
Buku Teks
edited by James A. Gould
Merril Publishing, 1989
Buku Referensi
Barnes, Winston H.F.
Adam & Charles Black, 1950
Buku Teks
Langer, Susanne K.
John Hopkins Press, 1964
Buku Teks
Ayer, Alfred Jules, 1910-1989
Penguin Books, 1982
Buku Teks