ZholtkevichG. N., NovikovB. V., and PolyakovaL. Yu. 2014. “Decomposition of Directed Graphs and the Turán Problem”. Ukrains’kyi Matematychnyi Zhurnal 66 (7), 958–969. https://umj.imath.kiev.ua/index.php/umj/article/view/2191.