There is a source for 18000 members in 2017 in the Wikipedia article [0], see footnote 11. The "Bundeszentrale für Politische Bildung" [1] is a reputable source

There is a source for 18000 members in 2017 in the Wikipedia article [0], see footnote 11. The "Bundeszentrale für Politische Bildung" [1] is a reputable source. [0] https://en.wikipedia.org/wiki/Grey_Wolves_(organization)#Germany https://en.wikipedia.org/wiki/Grey_Wolves_(organization)#Ger... [1] https://en.wikipedia.org/wiki/Federal_Agency_for_Civic_Education https://en.wikipedia.org/wiki/Federal_Agency_for_Civic_Educa...