Lee & Zee (2003),第109–110頁. Lee, Wai-Sum; Zee, Eric, Standard Chinese (Beijing), Journal of the International Phonetic Association, 2003, 33 (1): 109–112, doi:10.1017/S0025100303001208
Recasens & Espinosa (2007),第144頁. Recasens, Daniel; Espinosa, Aina, An electropalatographic and acoustic study of affricates and fricatives in two Catalan dialects, Journal of the International Phonetic Association, 2007, 37 (2): 143–172, doi:10.1017/S0025100306002829