Bukenov, M.M., and Bakaуeva G.B. “Chart of Breaking up for Three-Dimensional Task to Heat Conductivity”. Bulletin of the Karaganda University. Mathematics Series, vol. 78, no. 2, June 2015, pp. 36-39, http://mts.buketov.edu.kz/index.php/mathematics-vestnik/article/view/20.