I have a copy of an Italian monochrome print (1920s) showing 4 youths playing cards with a cheat occurring by the passing of a card under the table by foot. How can I determine the origin of the original print?
Are you thinking of capodimonte porcelain figurines, such as this one, based on a sculpture by Italian Bruno Merli?
The only thing I can find that comes remotely close as a monochrome photo is this picture of Prince Leopold, (1853 - 1884), (second from left), the youngest son of Queen Victoria, playing cards at Oxford. He was created Duke of Albany in 1881. His companions are Dalyrimple (left), W. J. D. Campbell (standing), and Lord Brooke (right).
I would take a photo of the print, crop it accurately (to avoid removing or leaving too much of the margin), and "search by image" to find similar photo in Google and Bing.