Clements, J. F., T. S. Schulenberg, M. J. Iliff, D. Roberson, T. A. Fredericks, B. L. Sullivan, and C. L. Wood (2014) The eBird/Clements checklist of birds of the world: Version 6.9 http://www.birds.cornell.edu/clementschecklist/download, läst 2015-02-01
doi.org
doi.org
Ramos-Ordoñez, M. F., C. I. Rodríguez-Flores, C. A. Soberanes-González, M. d. C. Arizmendi, and T. S. Schulenberg (2021). Black-headed Siskin (Spinus notatus), version 1.1. In Birds of the World (T. S. Schulenberg, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.blhsis1.01.1
Birdlife International 2016 Spinus notatus Från: IUCN 2016. IUCN Red List of Threatened Species. Version 2016.3 www.iucnredlist.org. Läst 11 december 2016.
iucnredlist.org
Birdlife International 2016 Spinus notatus Från: IUCN 2016. IUCN Red List of Threatened Species. Version 2016.3 www.iucnredlist.org. Läst 11 december 2016.