Sphyrapicus thyroideus (Cassin 1852)

The birds of North America New York, U.S.A. :Published under the auspices of the Natural Science Association of America,1895, c1888. biodiversitylibrary.org/page/41959147

The new and heretofore unfigured species of the birds of North America New York :Published by the author,1869. biodiversitylibrary.org/page/54294354

The birds of North America New York :Published under the auspices of the Natural Science Association of America,1903. biodiversitylibrary.org/page/35159789

Monographie des picidées, ou Histoire naturelle des picidés, picumninés, yuncinés ou torcols;. Metz,Typ. de J. Verronnais,1861-62.. biodiversitylibrary.org/page/40019203