Harbert, Wayne Eugene (2007). The Germanic Languages. Cambridge Language Surveys. Cambridge / New York: Cambridge University Press. pp. 15–17.
ethnologue.com
When taking all West Central German dialects as listed by Ethnologue the number 15.350,000 appears, 2 dialects have no speaker data, however considering the area in which they are spoken and the demographics of the area as well as comparable dialects an estimate of about 4,000,000 can be made.
