Verhoeven (2007), p. 220. Verhoeven, Jo (2007), "The Belgian Limburg dialect of Hamont", Journal of the International Phonetic Association, 37 (2): 219–225, doi:10.1017/S0025100307002940
Collins & Mees (2003:191). Goeman & Van de Velde (2001) have also found that frication is much more commonly in the velar region in dialects and language varieties with "hard G", though they do not distinguish between trilled and non-trilled fricatives in their study. Collins, Beverley; Mees, Inger M. (2003) [First published 1981], The Phonetics of English and Dutch (5th ed.), Leiden: Brill Publishers, ISBN978-9004103405 Goeman, Ton; Van de Velde, Hans (2001). "Co-occurrence constraints on /r/ and /ɣ/ in Dutch dialects". In van de Velde, Hans; van Hout, Roeland (eds.). 'r-atics. Brussels: Etudes & Travaux. pp. 91–112. ISSN0777-3692. {{cite book}}: |journal= ignored (help)
Collins & Mees (2003:191). Goeman & Van de Velde (2001) have also found that frication is much more commonly in the velar region in dialects and language varieties with "hard G", though they do not distinguish between trilled and non-trilled fricatives in their study. Collins, Beverley; Mees, Inger M. (2003) [First published 1981], The Phonetics of English and Dutch (5th ed.), Leiden: Brill Publishers, ISBN978-9004103405 Goeman, Ton; Van de Velde, Hans (2001). "Co-occurrence constraints on /r/ and /ɣ/ in Dutch dialects". In van de Velde, Hans; van Hout, Roeland (eds.). 'r-atics. Brussels: Etudes & Travaux. pp. 91–112. ISSN0777-3692. {{cite book}}: |journal= ignored (help)