Lee, Wai-Sum (1999). An articulatory and acoustical analysis of the syllable-initial sibilants and approximant in Beijing Mandarin (PDF). Proceedings of the 14th International Congress of Phonetic Sciences. S2CID 51828449. https://www.internationalphoneticassociation.org/icphs-proceedings/ICPhS1999/papers/p14_0413.pdf
Árnason (2011), p. 115. - Árnason, Kristján (2011), The Phonology of Icelandic and Faroese, Oxford University Press, ISBN 978-0-19-922931-4
Árnason (2011), p. 115. - Árnason, Kristján (2011), The Phonology of Icelandic and Faroese, Oxford University Press, ISBN 978-0-19-922931-4
Árnason (2011), p. 115. - Árnason, Kristján (2011), The Phonology of Icelandic and Faroese, Oxford University Press, ISBN 978-0-19-922931-4
Trudgill (1989), pp. 18–19. - Trudgill, Peter (1989), "The Sociophonetics of /l/ in the Greek of Sphakiá", Journal of the International Phonetic Association, 15 (2): 18–22, doi:10.1017/S0025100300002942, S2CID 143943154 https://doi.org/10.1017%2FS0025100300002942
Sadowsky et al. (2013), p. 90. - Sadowsky, Scott; Painequeo, Héctor; Salamanca, Gastón; Avelino, Heriberto (2013), "Mapudungun", Journal of the International Phonetic Association, 43 (1): 87–96, doi:10.1017/S0025100312000369 https://doi.org/10.1017%2FS0025100312000369
Sadowsky et al. (2013), p. 90. - Sadowsky, Scott; Painequeo, Héctor; Salamanca, Gastón; Avelino, Heriberto (2013), "Mapudungun", Journal of the International Phonetic Association, 43 (1): 87–96, doi:10.1017/S0025100312000369 https://doi.org/10.1017%2FS0025100312000369
Brandão, Silvia Figueiredo (15 December 2007). "Nas trilhas do -R retroflexo". Signum: Estudos da Linguagem. 10 (2): 265. doi:10.5433/2237-4876.2007v10n2p265. https://doi.org/10.5433%2F2237-4876.2007v10n2p265
Ferraz, Irineu da Silva (2005). Características fonético-acústicas do /r/ retroflexo do portugues brasileiro : dados de informantes de Pato Branco (PR) (Thesis). hdl:1884/3955. https://acervodigital.ufpr.br/handle/1884/3955
(in Portuguese) Syllable coda /r/ in the "capital" of the paulista hinterland: sociolinguistic analisis. Archived 2013-09-26 at the Wayback Machine Cândida Mara Britto LEITE. Page 111 (page 2 in the attached PDF) http://cedae.iel.unicamp.br/revista/index.php/sinteses/article/download/1198/1766
(in Portuguese) Callou, Dinah. Leite, Yonne. "Iniciação à Fonética e à Fonologia". Jorge Zahar Editora 2001, p. 24
Keane (2004), p. 111. - Keane, Elinor (2004), "Tamil", Journal of the International Phonetic Association, 34 (1): 111–116, doi:10.1017/S0025100304001549 https://doi.org/10.1017%2FS0025100304001549