Popham, W. James, author
Association for Supervision and Curriculum Developmen, 2001
Buku Teks
Ploscowe, Morris, author
Hawthorn Books, 1955
Buku Teks
tranlated from the Russion by H. Chizhevsky
Progress Publishers, 1977
Buku Teks
Shacford, R.H., author
Public Affairs Press, 1952
Buku Teks
Lumumba, Patrice, author
Foreign Languages Publishing Hose, 1961.
Buku Teks