www.ethnologue.com是International Linguistics Center建立的网站，从1951年收开始，录和整理了世界上的各种语言7000多种。记录了每种语言的基本信息：地理位置、人口、濒危程度、国际代码等，蔚为大观。暂存于此，备查。

The exact number of unwritten languages is hard to determine. Ethnologue (19th edition) has data to indicate that of the currently listed 7,097 living languages, 3,748 have a developed writing system. We don't always know, however, if the existing writing systems are widely used. That is, while an alphabet may exist there may not be very many people who are literate and actually using the alphabet. The remaining 3,349 are likely unwritten.