References
Willem Grootaers
(1957). Linguistic geography of the 宣化 Hsuan-Hua region: (察哈爾 Chahar province). Bulletin of the Institute of History and Philology Academia Sinica, 29, 59-86.
(1957). Linguistic geography of the 宣化 Hsuan-Hua region: (察哈爾 Chahar province). Bulletin of the Institute of History and Philology Academia Sinica, 29, 59-86.