I'm writing a paper for real analysis seminar, a paper about Banach-Zarecki theorem and I need some information about the authors.
Stefan Banach - there is no problem to find information about him.
What about Zarecki? I only found that he was russian mathematician, and in "Theory of functions of a real variable" Natanson writes "M. A. Zarecki". This is all I know - I cannot find any information about this mathematician or his life.