1. Ainsworth, S. (1975). Intrinsic and extrinsic factors in vowel judgments. In G. Fant & M. A. A. Tatham (Eds.), Auditory analysis and the perception of speech (pp. 103–113). London: Academic Press.
2. Assmann, P. F., & Nearey, T. M. (2003a). Frequency shifts and vowel identification. In Proceedings of the 15th International Congress of Phonetic Sciences (pp. 1397–1400). Barcelona.
3. Assmann, P. F., & Nearey, T. M. (2003b). A review of results on frequency shifts and vowel identification. Canadian Acoustics, 31, 18–19.
4. Assmann, P. F., & Nearey, T. M. (2007). Relationship between fundamental and formant frequencies in voice preference. Journal of the Acoustical Society of America, 122, EL35-EL43. Retrieved May 8, 2009, from http://scitation.aip.org/journals/doc/JASMAN-ft/vol_122/iss_2/EL35_1.html. doi:10.1121/1.2719045
5. Assmann, P. F., Nearey, T. M., & Dembling, S. (2006). Effects of frequency shifts on perceived naturalness and gender information in speech. In Proceedings of the 9th International Conference on Spoken Language Processing (pp. 889–892). Pittsburgh.