1. Aichert, I., & Ziegler, W. (2004). Syllable frequency and syllable structure in apraxia of speech. Brain and Language, 88(1), 148–159.
2. Baayen, R. H., Piepenbrock, R., & van Rijn, H. (1993). The Celex lexical database (CD-ROM). University of Pennsylvania, Philadelphia: Linguistic Data Consortium.
3. Balota, D. A., Yap, M. J., Cortese, M. J., Hutchison, K. A., Kessler, B., Loftis, B., ... Treiman, R. (2007). The English Lexicon Project. Behavior Research Methods, 39, 445–459.
4. Barca, L., Burani, C., & Arduino, L. S. (2002). Word naming times and psycholinguistic norms for Italian nouns. Behavior Research Methods, Instruments, and Computers, 34(3), 424–434.
5. Bertinetto P. M., Burani C., Laudanna A., Marconi L., Ratti D., Rolando C., & Thornton A. M. (2005). Corpus e Lessico di Frequenza dell'Italiano Scritto (CoLFIS). http://linguistica.sns.it/CoLFIS/CoLFIS_home.htm