Reconstructing Achumawi and Atsugewi - Linguistics paper on the Palaihnihan languages. PDF format. - http://email.eva.mpg.de/~good/jcgood_mcfarland_paster-Palainihan.pdf
Achumawi Language and the Pit River Tribe - Pronunciation guide, language learning worksheets, and cultural information. - http://www.native-languages.org/achumawi.htm
Wikipedia: Achumawi language - Article including Achumawi family relationships and linguistic bibliography. - http://en.wikipedia.org/wiki/Achumawi_language
Ethnologue: Achumawi - Basic demographic and linguistic information. - http://www.ethnologue.com/show_language.asp?code=acv