Popovych, R.     Multiplicative order of elements in towers of finite fields of characteristic [Текст] / R. Popovych // X International algebraic conference in Ukraine, dedicated to the 70th anniversary of Yu. A. Drozd : abstracts, Aug. 20-27, 2015, Odessa, Ukraine / Inst. of Mathematics of NAS of Ukraine, T. Shevchenko Nat. Univ. of Kyiv, I. I. Mechnikov Odessa Nat. Univ. — Odessa : TES, 2015. — P. 90.