Rada, Juan. “Ordering Catacondensed Hexagonal Systems With Respect to VDB Topological Indices”. Revista de Matemática: Teoría y Aplicaciones 23, no. 1 (April 19, 2017): 277–289. Accessed August 16, 2024. https://revistas.ucr.ac.cr/index.php/matematica/article/view/22554.