Thomas (2001),第27–28, 61–63頁. Thomas, Erik R., An acoustic analysis of vowel variation in New World English, Publication of the American Dialect Society (Duke University Press for the American Dialect Society), 2001, 85, ISSN 0002-8207
Thomas (2001),第27–28, 73–74頁. Thomas, Erik R., An acoustic analysis of vowel variation in New World English, Publication of the American Dialect Society (Duke University Press for the American Dialect Society), 2001, 85, ISSN 0002-8207
Thomas (2001),第27–28, 112–115, 121, 134, 174頁. Thomas, Erik R., An acoustic analysis of vowel variation in New World English, Publication of the American Dialect Society (Duke University Press for the American Dialect Society), 2001, 85, ISSN 0002-8207