The International encyclopedia of education
Husen, T.
The International encyclopedia of education research and studies Vol 7 P-R T. Husen - ed. I - Newyork Peragamon Press 1985 - ix,3737-43
The International encyclopedia of education research and studies Vol 7 P-R T. Husen - ed. I - Newyork Peragamon Press 1985 - ix,3737-43