^Schuessler, Axel (2014) "Phonological Notes on Hàn Period Transcriptions of Foreign Names and Words" in Studies in Chinese and Sino-Tibetan Linguistics: Dialect, Phonology, Transcription and Text. Series: Language and Linguistics Monograph. Issue 53. p. 257 of 249-292
^Pulleyblank, Edwin G. (1983). "The Chinese and Their Neighbors in Prehistoric and Early Historic China," in The Origins of Chinese Civilization, University of California Press, p. 452 of pp. 411–466.
^Shimunek, Andrew (2017). Languages of Ancient Southern Mongolia and North China: a Historical-Comparative Study of the Serbi or Xianbei Branch of the Serbi-Mongolic Language Family, with an Analysis of Northeastern Frontier Chinese and Old Tibetan Phonology. Wiesbaden: Harrassowitz Verlag. ISBN978-3-447-10855-3. OCLC993110372.