↑Hammarström, Harald; Forkel, Robert; Haspelmath, Martin, ed. (2023). "Lembah Cagayan". Glottolog 4.8. Jena, Jerman: Max Planck Institute for the Science of Human History. ; ;
Daftar pustaka
Robinson, Laura C. and Jason William Lobel (2013). "The Northeastern Luzon Subgroup of Philippine Languages." Oceanic Linguistics 52.1 (2013): 125-168.