Hogstad, Olav. “Sexual Bill Dimorphism Supports Separation of the Woodpecker Genera Dendrocopos Koch (1816) in the Palaearctic and Picoides Lacépède (1799) in the Nearctic”. Ornis Norvegica 31 (January 1, 2008): 183–188. Accessed April 18, 2024. https://boap.uib.no/index.php/ornis/article/view/167.