Leonard, Karen Isaksen, author
Sage, 2003
Buku Teks
Vincent, Andrew
Basil Blackwell, 1987
Buku Teks
Laski, Harold J., author
George Allen and Unwin, 1935
Buku Teks
Seckler-Hudson, Catheryn, author
United State Information Service, 1959
Buku Teks
Holloway, William Vernon, author
McGraw-Hill , 1951
Buku Teks