Howykowycz, Mariya     Construction of invariant difference and discrete analogues of differential operators of high order discretization error [Текст] / Mariya Howykowycz // Computational problems of electrical engineering (CPEE'2011) : proc. of the 12th Intern. symp., Sept. 5-7, 2011, Kostryno, Ukraine / Lviv Polytechnic Nat. Univ., Warsaw. Univ. of Technology, Techn. Univ. of Lodz, Univ. of West Bohemia. — Lviv : Lviv Polytechnic Nat. Univ., 2011. — P. 6.