(en) Michael Everson, Proposal to add six phonetic characters for Scots to the UCS (no N5036R L2/19-075R), (lire en ligne)
(en) International Phonetic Association, Handbook of the International Phonetics Association : A Guide to the Use of the International Phonetic Alphabet, Cambridge, Cambridge University Press, , 204 p. (ISBN0-521-63751-1)