Williams H, Robins CW, Newman AEM, mfl. The buzz segment of Savannah sparrow song is a population marker. Journal of Ornithology. 2018. Available at: http://link.springer.com/10.1007/s10336-018-1611-7.

Ciaburri I, Williams H. Context-dependent variation of house finch song syntax. Animal Behaviour. 2019;147:33 - 42. Available at: https://linkinghub.elsevier.com/retrieve/pii/S0003347218303373https://api.elsevier.com/content/article/PII:S0003347218303373?httpAccept=text/xmlhttps://api.elsevier.com/content/article/PII:S0003347218303373?httpAccept=text/plain.