Reference

Hannah Joy Kriesell, Celine Le Bohec, Alexander F. Cerwenka, Moritz Hertel, Jean-Patrice Robin, Bernhard Ruthensteiner, Manfred Gahr, Thierry Aubin, Daniel Normen Düring (2020): Vocal tract anatomy of king penguins: morphological traits of two-voiced sound production – Frontiers in Zoology – 2020: 5-0001-5-0011.