Henry Jenner, Handbook of the Cornish Language, London 1904 full text
books.google.com
Eska, Joseph F. (2006). "Galatian language". In John T. Koch (ed.). Celtic culture: a historical encyclopedia. Vol. III: G—L. Santa Barbara, California: ABC-CLIO. ISBN1-85109-440-7.
"A Typological Evaluation of Celtic/Hamito-Semitic Syntactic Parallels", Ph.D. Dissertation, University of California, Berkeley, 1993 https://escholarship.org/uc/item/8p00g5sd
"Celtic and Afro-Asiatic" in The Celtic Languages in Contact, Papers from the Workshop within the Framework of the XIII International Congress of Celtic Studies, Bonn, 26–27 July 2007, p. 25-80 full text
All other research into Pictish has been described as a postscript to Buchanan's work. This view may be something of an oversimplification: Forsyth 1997 offers a short account of the debate; Cowan & McDonald 2000 may be helpful for a broader view. Forsyth, Katherine (1997). Language in Pictland : the case against 'non-Indo-European Pictish'. Studia Hameliana, 2. Utrecht: De Keltische Draak. ISBN9789080278554. OCLC906776861. Cowan, Edward J.; McDonald, R Andrew (2000). Alba : Celtic Scotland in the Middle Ages. East Linton: Tuckwell Press. ISBN9781862321519. OCLC906858507.