In my experience most instances of Isaac/Yitzchak are listed in the Polish
records as Ick/Jck or Idzk/Jdzk.
From: "David Ellis" <firstname.lastname@example.org
Date: Sun, 1 Dec 2013 08:35:14
Here's a tip if you're trying to find a record in JRI-Poland for a
relative with the given name Isaac or Yitzchak. There are multiple
spellings in the records. The corresponding name in Polish is often
spelled Icek or Iciek, but sometimes it is rendered Jciek. The D-M
"sounds like" searches yield different results when you look for
records with given names sounding like Iciek and Jciek. You'll want
to search for both!
David J Ellis=