CROFT, W. (1996). Typology and universals. Cambridge University Press.
Lua i Stíl Chicago (17ú heag.)CROFT, William. Typology and Universals. Cambridge: Cambridge University Press, 1996.
Lua MLA (9ú heag.)CROFT, William. Typology and Universals. Cambridge University Press, 1996.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.