Czech Art Historians … Benes Knuepfer (Prague)

Hello everyone. I am wondering if anyone out there is a expert or versed in Czech art history, turn of Protected content . My great grandfather's cousin was Benes Knuepfer a turn of the Protected content Czech painter who is pretty well known for his work for the period. I am trying to find out if any of his work is still in Prague. I know it is in Dusseldorf and Vienna, but I turned up nothing my first trip to Prague. Eventually I would like to purchase a piece, to have some family history on hand.

If any one can help me track down my, I guess 4th cousin's work, I would be grateful, and any help tracking one of the paintings down available for public viewing or a kind private collector letting a relative see his relatives work up close and personal, I will gladly host for dinner, or bottle of wine. :)

Thank you all.