There are many books and websites where you can learn more about linguistic diversity, language endangerment, and language documentation. We recommend the following (see also the reference sections of the chapters in the Book of Knowledge):
Books in English
Online
- Dryer, Matthew & Haspelmath, Martin (eds.) 2013. The World Atlas of Language Structures Online. Munich: Max Planck Digital Library.
- Lewis, M. Paul, Simons, Gary F. & Fennig, Charles D. (eds.). 2014. Ethnologue. Languages of the World. 17th edition. Dallas, Texas: SIL International. Online version.
- Moseley, Christopher (ed.) 2010. Atlas of the World’s Languages in Danger, 3rd ed. Paris, UNESCO Publishing. Online version.
Print (the first two most recommended as especially comprehensive and accessible)
- Crystal, David 2010. The Cambridge Encyclopedia of Language. Cambridge: Cambridge University Press.
- Evans, Nicholas. 2010. Dying Words. Endangered languages and what they have to tell us. Malden & Oxford: Wiley-Blackwell.
- Crystal, David. 2000. Language death. Cambridge: CUP.
- Harrison, K. David. 2007. When languages die: The extinction of the world’s languages and the erosion of human knowledge. Oxford: Oxford University Press.
- Nettle, Daniel & Suzanne Romaine. 2000. Vanishing voices. The extinction of the world’s languages. Oxford: Oxford University Press.
Books in Polish
- Maciejewski, Witold 1999. Wielka Encyklopedia Geografii Świata. Tom XIV: Świat Języków. Poznań: Wydawnictwo Kurpisz.
- Majewicz, Alfred F. 1989. Języki świata i ich klasyfikowanie. Warszawa: PWN.
Websites in English and in other languages
Information on endangered languages (websites for non-specialists and educational sites):
- SOROSORO. So the languages of the world may live on! Online directory on selected endangered languages and very good videos. Also general information on languages and linguistics. Site in French, English, and Spanish.
- Endangered Languages by the Alliance for Linguistic Diversity. This site provides short information about a great number of languages and offers audio, video and text samples for many of them.
- Babelfisch. Der Weltemfpänger für die Stimmen der Welt. A German website with information on various languages, with audio samples.
- Bedreigde Talen / Endangered Languages. Online material for learning and teaching about endangered languages, available in English, Dutch, Spanish, Brazilian Portuguese, and Russian.
- The Linguists. This website accompanies an educational film and offers material for learning and teaching about endangered languages.
- Living Tongues. Website of a private non-profit institution dedicated to the preservation of endangered languages.
- Enduring Voices. A professionally made website belonging to the magazine National Geographic, cooperates with the Living Tongues Institute.
- Endangered Language Alliance. Website of an independent organization based in New York and focusing on endangered languages in urban areas.
- The SOAS Radio offers podcasts about endangered languages and cultures for listening and downloading.
Documentation of endangered languages: Archives and information about projects