BONDARENKO А.В., DMITRENKO И.М., OBOLENSKY М.А., TOVAZHNY-ANSKIl В.Л., FOGEL` Н.Я. and CHERKASOVA В.Г. 1989. Anisotropy of H_c2 and resistive transitions in orthorhombic and tetragonal single crystals of YBa₂Cu₃O_x. FIZYKA NYZKYKH TEMPERATUR. 15, 6 (Jun. 1989), 582–587.