Tyler, Ralph W.
University of Chicago, 1949
Buku Teks
John Macbeath, Neil Dempster
Routledge, 2009
Buku Teks
Leese, Joseph
Harper & Row, 1961
Buku Teks
Taba, Hilda, author
Harcourt Brece & World, 1962
Buku Teks
Nicholls, Audrey, author
George Allen and Unwin, 1972
Buku Teks