Marushchak, Yaroslav     Approximation of fractional order differential-integral controllers by integer order transfer functions [Текст] / Yaroslav Marushchak, Bohdan Kopchak // Computational problems of electrical engineering / Lviv Polytechnic nat. univ. ; ed.-in-chief Yuriy Bobalo. — Lviv : lviv Polytechnic nat. univ., 2012. — P. 29-32.