Monge-Nájera, Julián, and Francisco Hernández. 1994. “Spatial Organization of the Structural Color System in the Quetzal, <i>Pharomachrus mocinno</i≫ (Aves: Trogonidae) and Evolutionary Implications”. Revista De Biología Tropical 42 (S2):131–139. https://revistas.ucr.ac.cr/index.php/rbt/article/view/28711.