Watt, Alan, author
Sydney Angus and Robertson 1972
Buku Teks
Loehwing, Walter F.
University of Iowa Press , 1947
Buku Teks
Panikkar, K.M., author
George Allen and Unwin, 1955
Buku Teks
Eastman, Max, 1883-1969, author
Farrar Straus and Cudahy, 1942
Buku Teks
Jenks, Albert Ernest
American Association, 1937
Buku Teks