Walter, Paul A.F., author
McGraw-Hill, 1952
Buku Teks
Banton Michael, author
Tavistock Publications, 1969
Buku Teks
Mason, Philip, author
Oxford University Press, 1970
Buku Teks
Wade, Peter, author
Pluto Press, 2002
Buku Teks
Park, Robert Ezra, author
The Free Pressof Glencoe, 1950
Buku Teks