Schwartz, Louis B., author
The Foundation , 1966
Buku Teks
Saxton, C. Clive
Oxford University Press, 1942
Buku Teks
Levy, Hermann
Macmillan, 1927
Buku Teks
Handley, Eleanor M.
Princeton University Press , 1970
Buku Teks
This, Leslie E.
Addison-Wesley Pub. Co. , 1974
Buku Teks