Plamenatz, John
Longman, 1991
Buku Teks
Maritain, Jacques
The University of Chicago Press, 1951
Buku Teks
Simons, David G.
New York: Doubleday, 1960
Buku Teks
Dorrestein, Renate
uitgeverij contact, 1995
Buku Teks
Nesturkh, M. F. (Mikhail Fedorovich), author
Progress Publishers, 1967
Buku Teks