Rieger, R.
Springer-Verlag, 1991
Buku Teks
Andersen, Dines
Copenhagen: Gyldendalske Boghandel, 1907
Buku Teks
American Psychiatric Press, 1984
Buku Referensi
Redden, Kenneth R., author
The Michie Company, 1980
Buku Referensi
New York Institute of Finance, 1988
Buku Teks