Michelena, Luis. 1961. Fonética Histórica Vasca. San Sebastián: Diputación de Guipúzcoa; Forni, Gianfranco, "A First Etymological Dictionary of Basque as an Indo-European Language. Basque Native, Basic Lexicon", 2016, ISBN 9781499595468;
Michelena, Luis. 1961. Fonética Histórica Vasca. San Sebastián: Diputación de Guipúzcoa; Bengtson, John D., "Notes on Basque Comparative Phonology. Mother Tongue 8", 2003: 21-39; Forni, Gianfranco, "A First Etymological Dictionary of Basque as an Indo-European Language. Basque Native, Basic Lexicon", 2016, ISBN 9781499595468;
Ferrer, J.; Moncunill, N. (28 de febrero de 2019), «Palaeohispanic writing systems», Palaeohispanic Languages and Epigraphies (Oxford University Press): 78-108, consultado el 28 de julio de 2023.