Gyug, L.W., R. C. Dobbs, T. E. Martin, and C. J. Conway. 2012. Williamson's Sapsucker (Sphyrapicus thyroideus), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/species/285. doi:10.2173/bna.285
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