"With printing being as well developed as it is in the West, the forgery of Soviet identification papers is nothing. A friend of mine even went as far as forging American dollars. And you know how difficult that is. The paper has those different-coloured little lines on it. It requires great technique. He managed to get rid of them on the Moscow black market, but it turned out later that his grandfather, a notorious currency-dealer, had bought them all in Kiev and gone absolutely broke. The dollars were counterfeit, after all."
January 1, 1970
https://en.wikiquote.org/wiki/Ilf_and_Petrov