Kepping K. B. The category of directness of action in Tangut (prefixes-correlates of aspect and mood) // Петербургское востоковедение. Выпуск 5. СПб.: Центр «Петербургское Востоковедение», 1994. С. 267—291.
1a. A system of verbal affixes denoting direction of action
(direction indicators) seems to represent a characteristic feature of the
languages spoken in a vast region in Central Asia. This phenomenon, in
the form of prefixes, is widely spread among the languages of the so-called
Chuanxi minzu zoulang in China (Sun, 1990: 23—4), whereas, in
the form of suffixes, it exists in such Tibeto-Burman languages as Deng
(Sun, et al., 1980: 208) and, as recent expeditions have shown, in some
Himalayan languages as well (Bickel, forthcoming; Rutgers, forthcoming)...