Milov, A. “Optimized Algorithms of Haar’s Discrete Transforms for the Russian «ELCORE» DSpdf and Their Applications in Image Processing”. Numerical Methods and Programming (Vychislitel’nye Metody I Programmirovanie), vol. 8, no. 13, Apr. 2007, pp. 34-39, https://en.num-meth.ru/index.php/journal/article/view/283.