one question to Polish coins: according KM and also according Numista catalogue the 10 groszy of Poland of 1923 are made of Nickel resp. Nickel plated steel. Nr. Y-11.
But I have these coins looking like made of Zinc. Not magnetic.
Whenever you can not find the coin you have, you can go to search and write something like: "poland 10 1923". Most of the times, the coin will be displayed there.