N. Safronov, G. . “The Formation of Spherical Graphite in Cast Irons With the Economy of Rare Earth Metals”. Helix - The Scientific Explorer | Peer Reviewed Bimonthly International Journal, vol. 9, no. 04, Aug. 2019, pp. 5175-7, https://helixscientific.pub/index.php/home/article/view/14.