Hawley, Amos H.
The University of Chicago Press, 1986
Buku Teks
Zipf, George Kingsley
Hafner, 1965
Buku Teks
Program Pascasarjana Universitas Indonesia, 1994
Majalah, Jurnal, Buletin
edited by Gwen Bell
Hawaii University Press, 1976
Buku Teks
The Association for Supervision and Curriculum Development, 1978
Buku Teks