Monge, Julián. “The Persistent Embrace of Onychophorans: What Determines Copulation Duration in Velvet Worms?”. Revista de Biología Tropical, no. 1 (February 13, 2019): Darwin. Accessed March 28, 2025. https://revistas.ucr.ac.cr/index.php/rbt/article/view/36161.