Phonetic Association: A Guide to the usage of the International Phonetic Alphabet., Cambridge: Cambridge University Press: 140–142, 1999, ISBN 978-0-521-63751-0
ISBN 978-0-8264-8873-2, (原始内容存档于2019-06-08) Ternes, Elmer; Vladimirova-Buhtz, Tatjana, Bulgarian, Handbook of the International Phonetic Association, Cambridge University
Phonetic Association: A guide to the use of the International Phonetic Alphabet, Cambridge: Cambridge University Press: 70–74, 1999, ISBN 0-521-65236-7
Phonetic Association: A guide to the use of the International Phonetic Alphabet, Cambridge: Cambridge University Press: 70–74, 1999, ISBN 0-521-65236-7