G. C. L. M. Bakkum, The Latin dialect of the Ager Faliscus: 150 years of scholarship, Volume 2, University of Amsterdam Press, 2009, p. 1 for estimated number or inscriptions, p. 393ff. for Ceres inscription, and p. 406 for its general acceptance as the oldest example of Faliscan dialect. googlebooks preview
glottolog.org
Hammarström, Harald; Forkel, Robert; Haspelmath, Martin, (Ed.) (2017). "Faliscan". Glottolog 3.0. Jena, Germany: Max Planck Institute for the Science of Human History.