Havinga, A., & Langer, N. (2015). Invisible languages in the nineteenth century. Peter Lang.
Lua i Stíl Chicago (17ú heag.)Havinga, Anna, agus Nils Langer. Invisible Languages in the Nineteenth Century. Oxford, [England]: Peter Lang, 2015.
Lua MLA (9ú heag.)Havinga, Anna, agus Nils Langer. Invisible Languages in the Nineteenth Century. Peter Lang, 2015.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.