Szpyrka, Marcin, Piotr Matyasik, Jerzy Biernacki, Agnieszka Biernacka, Michał Wypych, and Leszek Kotulski. 2016. “Hierarchical Communication Diagrams”. Computing and Informatics 35 (1):55-83. http://147.213.75.17/ojs/index.php/cai/article/view/2961.