San Martín, G., and S. Estapé. “Redescription of <i>Pionosyllis procera</i≫ (Polychaeta: Syllidae), With Comments on Its Reproduction and Systematic Position”. Revista De Biología Tropical, vol. 41, no. 2, Aug. 1993, pp. 227–231, https://revistas.ucr.ac.cr/index.php/rbt/article/view/23356.