Comment: Other relevant forms: Ag. Bursh. χI:uj, Tsakh. Gelm. χʷajä. In PL there existed a parallel oblique base *χ:ʷäj-rV-, cf. Ag. Bursh. χI:ura-ni-, whence the Kryz. and Bud. direct forms with -r.
See Trubetzkoy 1930, 85; Лексика 1971, 158; Гигинейшвили 1977, 121.