Citation Hunt

The Wikipedia snippet below is not backed by a reliable source. Can you find one?

Click I got this! to go to Wikipedia and fix the snippet, or Next! to see another one. Good luck!

In page Sudetes:

"

The term was used in a wider sense when on 1 October 1933 Konrad Henlein founded the Sudeten German Party and in Nazi German parlance Sudetendeutsche (Sudeten Germans) referred to all indigenous ethnic Germans in Czechoslovakia. They were heavily clustered in the entire mountainous periphery of Czechoslovakia—not only in the former Moravian Provinz Sudetenland but also along the northwestern Bohemian borderlands with German Lower Silesia, Saxony and Bavaria, in an area formerly called German Bohemia. In total the German minority population of pre-World War II Czechoslovakia numbered around 20% of the total national population.