Горбійчук, М. І., and М. О. Слабінога. “USING RECTANGULAR ORTHOGONAL FUNCTIONS FOR THE TECHNICAL EVALUATION OF INDUSTRIAL FACILITIES”. METHODS AND DEVICES OF QUALITY CONTROL, no. 1(30), May 2013, pp. 92-97, https://mpky.nung.edu.ua/index.php/mpky/article/view/163.