https://finchdiaries.wordpress.com/tag/salmon-headed-gouldian/
http://www.gouldianfinches.eu/en/genetics-forecast/
https://www.thesprucepets.com/gouldian-finch-species-profile-390632
https://www.colorado.edu/today/2019/04/23/birds-break-evolutionary-rules-when-it-comes-feather-color