Wells (1975:52), Wells (1976:2) Wells, J. C. (1975). "The Association's Alphabet". Journal of the International Phonetic Association. 5 (2): 52–58. JSTOR44525810. Wells, J. C. (1976). "The Association's Alphabet". Journal of the International Phonetic Association. 6 (1): 2–3. JSTOR44525810.
Catford (1990:26-28) in reference to Roach (1989:73); Esling (1995:48) in reference to Roach (1993:33); though technically restorations of their short-lived placements from Passy & Jones (1921:6-7) Catford, J. C. (1990). "A Proposal Concerning Central Vowels". Journal of the International Phonetic Association. 20 (2): 26–28. JSTOR44526804. Roach, P. J. (1989). "Report on the 1989 Kiel Convention: International Phonetic Association". Journal of the International Phonetic Association. 19 (2): 67–80. JSTOR44526032. Esling, John (1995). "News of the IPA: Correction to the IPA Chart". Journal of the International Phonetic Association. 25 (1): 48. JSTOR44526850. Roach, P. J. (1993). "Council Actions on Revisions of the IPA". Journal of the International Phonetic Association. 23 (1): 32–34. JSTOR44594811. Passy, Paul; Jones, Daniel (1921). L’Écriture Phonétique Internationale: Exposé Populaire (2e ed.). Paris: Association Phonétique Internationale.