An excellent summary georgetown-magazine-article.pdf article - "Humanity's Hero Jan Karski" - which appeared in Georgetown Magazine in their Fall 2013 issue, by Sara Piccini
An article about an exhibit at the El Paso Holocaust Museum that features Jan Karski and others who tried to or did rescue Jews
The US Holocaust Memorial Museum's website has a section on Karski, including a photo of Karski and General Colin Powell, whom he met during the opening ceremonies of the Museum.
An Op Ed in the New York Times by former Secretary of State Madeleine Albright that mentions Karski and his resilience
An article from Deseret News that talks about Karski's and other Eastern European heroes' contributions and legacy