Комментарии:EAS 64, KW 419, Poppe 26, Martin 244, Menges 1984, 266, АПиПЯЯ 76. Jpn. tone is irregular; it may be, however, due to an influence of another root (cf. *čĕk`a, OJ toko 'always, eternally' /accent unknown/). Mong. čag may be < Turk. (see TMN 3, 27-28, Щербак 1997, 112), but may as well be genuine. The Kor. reflex is quite regular (the attested čǝk is just an orthographic variant of the expected *čjǝk), despite Doerfer's doubts in TMN ibid.
