Russell, Bertrand, 1872-1970, author
George Allen & Unwin Ltd, 1949
Buku Teks
Schumpeter, Joseph A.
Harper , 1950
Buku Teks
edited by David Clark
Open University Press , 1993
Buku Teks
Wilde, Lawrence, author
Dartmouth, 1994
Buku Teks
Ebenstein, William, author
Prentice-Hall, 1954
Buku Teks