Thanks to those who contacted me about Zelig Kost. According to
family lore, Kost became a partisan after the Nazis killed his family.
I found the following citation on the US Holocaust Memorial Museum
site, confirming this:

http://resources.ushmm.org/hsv/person_view.php?PersonId=4617047

However, I was unable to track down the "Jewish Partisans in Belarus
1941-1944" that was referenced on the page about Kost. It is credited
to JewishGen, electronic data regarding Belarus partisans, but a quick
search of the JewishGen site turned up nothing. If anyone can help,
and in particular if anyone could provide more information about
Jewish partisans in Belarus during the war, I'd be grateful.

David Laskin,
Seattle, WA