Martynenko, S. “The Package of Application Programs for the Robust Multigrid Technique: Building Blocks and Diagnostic Tools”. Numerical Methods and Programming (Vychislitel’nye Metody I Programmirovanie), vol. 2, no. 2, Dec. 2001, pp. 1-6, https://en.num-meth.ru/index.php/journal/article/view/43.