^De Vaan, Michiel (2008), “cohum”, inEtymological Dictionary of Latin and the other Italic Languages (Leiden Indo-European Etymological Dictionary Series; 7), Leiden, Boston: Brill,→ISBN,pages123-124: “*koχo-”
^Delamarre, Xavier (2003), “*kagyo-”, inDictionnaire de la langue gauloise: une approche linguistique du vieux-celtique continental [Dictionary of the Gaulish language: A linguistic approach to Old Continental Celtic] (Collection des Hespérides; 9), 2nd edition, Éditions Errance,→ISBN, page184: “*kagʰo-"”