Conrat, Heinz Fraenkel
Academic Press, 1962
Buku Teks
Helaine Selin
Springer Science, 2012
eBooks
edited by Chibueze C. Udeani ... [et al.]
Council for Research in Values and Philosophy,, 2006
Buku Teks
Foster, George M., author
Harper & Row , 1962
Buku Teks
Kaplan, Bert, author
Peabody Museum, 1954
Buku Teks