History / Circus in Warsaw 1930's; information for an elderly relative whose family were in that circus [8]

Hullo

I am just starting to research about a circus that I believe was in Warsaw before the WWII. I am hoping to find information for an elderly relative whose family were in that circus who ended up over here after the war, and for his family.

Any ideas where to start would be apprciated.

Thank you very much
Best wishes
Denise