One of the readers of my blog put up a link to an old article about Jan Karski, which was written in the year 2000.
You can also read about Jan Karski on this website: http://www.dailymail.co.uk/news/article-1383612/Jan-Karski-warned-Holocaust-1942-believed-him.html
Jan Karski is famous because he is the man who first TOLD THE WORLD ABOUT THE HOLOCAUST. No one knew that the Nazis were killing Jews, until Karski BROKE INTO AUSCHWITZ and told the world about this horror. I wrote about this on this blog post: https://furtherglory.wordpress.com/2015/11/10/jan-karski-is-back-in-the-news/
One of my very first blog posts, back in the 2012, was about Jan Karski: https://furtherglory.wordpress.com/2012/05/27/bob-dylan-and-jan-karski-to-receive-the-presidential-medal-of-freedom/
I also wrote about how Jan Karski told the world about the Holocaust in another blog post: https://furtherglory.wordpress.com/2015/08/31/jan-karski-the-man-who-first-told-the-world-about-the-holocaust/