Statement
Jan Karski entered the Warsaw ghetto and on 1 December 1942 informed the Polish government in exile in London.
Documented evidenceHigh certainty✓ Verified
References
p. 455
supports · main text · ch. 14
Efron, Lehmann and Weitzman. The Jews: A History. 3rd edition. New York and Abingdon: Routledge, 2019.
Verification anchor recorded · checked against the page text