Clauson (1972)
An etimological dictionary of pre-thirteenth-century Turkish
p. 319
VUF bokursı:
‘a wooden plough’. Survives only(?) in SE Türki bukusa BŞ 93; bokusa/bukusa Jarring 59; an odd-looking word, with no Turkish etymology; prob. a corruption of Tokharian A pyakas ‘a pointed stake’, van Windekens, Lexique étymologique des dialectes tokhariens, Louvain, 1941, p. 104. Cf. amaç. Türkü viii ff. eki: ökü:zü:g bir bokursuka: kölmiş ‘(a man) harnessed two oxen to one wooden plough’ (they stand still unable to move) IrkB 25: Xak. xi bokursı: al-man ‘a ploughshare’ Kaş. III 242.