TITLE: Banach-Zarecki theorem - who was Zarecki?
QUESTION [11 upvotes]: 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.

REPLY [13 votes]: Here's an excerpt from Integration and Modern Analysis by Benedetto and Czaja (pp. 202-203):

Moisej A. Zaretsky (1903–1930) is not a household name in mathematics, which is why we feature him now because of his beautiful result, independent of Banach, of the Banach–Zaretsky theorem (1925) (Theorem 4.6.2). Zaretsky was a Russian, and he died in the Caucasian resort of
  Batumi. The English translation of the Russian Isidor P. Natanson’s text
  uses the spelling “Zarecki” 

As a matter of fact, Zarecki is a Polish transliteration of his name -- most likely it was used by Banach and his group.