Lewis, Gary F. Simons, M. Paul & Charles D. Fennig. 2015. Ethnologue: Languages of the World. Eighteenth edition. Dallas: SIL International. (Online version: http://www.ethnologue.com).
@book{Lewisetal2015,
address = {Dallas},
author = {Lewis, M. Paul, Gary F. Simons & Charles D. Fennig},
note = {Online version: http://www.ethnologue.com},
publisher = {SIL International},
title = {Ethnologue: Languages of the World. Eighteenth edition},
year = {2015},
sections = {None}
}