Thanks a lot again. I know that parent asian elephants from Warsaw Zoo died during the WW2. However a book on zoo history in Poland from the 1970 says that both Jas and Kasia died in Warsaw zoo during the first days of the war. This source is much closer to the events both in time and geography. Therefore I am inclined to trust it.
Do you know what happened to a male nile hippo from Warsaw Zoo? Jan Zabinski in one of his popular books wrote in amazement, that this hippo, although a tropical animal, survived in broken, unheated pool and being loaded on transport by German troops in near-freezng temperatures.