1. Bamberger, R. & Vanecek, E. (1984). Lesen-Verstehen-LernenSchreiben [Reading-understanding-learning-writing].Vienna: Jugend & Volk.
2. Elliot, C. D. (1992).British Ability Scales: Spelling scale. Windsor, England: NFER-Nelson.
3. Elliot, C. D., Murray, D. J. & Pearson, L. S. (1983).British Ability Scales: Word Reading. Windsor, England: NFER-Nelson.
4. Harrison, C. (1980). Readability in the classroom.Berkeley: University of California Press.