Karski Jan

Resistance fighter. Member of the Polish underground, courier to the Polish Government-in-exile, slipped twice into the Warsaw ghetto in 1942 and subsequently made his way to London and the US to report on the deplorable conditions he witnessed. Righteous gentile. 

Story of a Secret State / J. Karski. - Boston : H. Mifflin, 1944. - p. 142, Encyclopedia of the Holocaust / ed. I. Gutman. - New York : Macmillan, 1990. - Vol. 2, p. 787