I found this New York times mag article really interesting.
A Closer Reading of Roman Visniac
Photographs by Roman Vishniac, from Mara Vishniac Kohn/International Center of Photography
“JEWISH MAN LOOKING THROUGH IRON DOOR, WARSAW, CIRCA 1935–38” Paired with the picture of the little boy at the right, this was one of Vishniac’s most famous shots. “BOY PLAYING, LODZ, CIRCA 1935–38” New evidence suggests that the two pictures are not connected.