F. Salazar-Hermoso and C. Villavicencio-Garayzar, “Relative abundance of the shovelnose guitarfish rhinobatos productus (Ayres, 1856) (Pisces: Rhinobatidae) in Bahía Almejas, Baja California Sur, from 1991 to 1995”, Cienc. Mar., vol. 25, no. 3, pp. 401–422, Mar. 1999.