Hanulíková, Adriana; Hamann, Silke (2010), "Slovak"(PDF), Journal of the International Phonetic Association, 40 (3): 373–378, doi:10.1017/S0025100310000162
Yanushevskaya, Irena; Bunčić, Daniel (2015), "Russian"(PDF), Journal of the International Phonetic Association, 45 (2): 221–228, doi:10.1017/S0025100314000395