i need help identifing these items. i found some old war bond advertisment printing plates made from led. There about 3in x 6in many different subjects. all of them say U.S. tresaury department on the bottom. some are comic strips about buying warbonds, others and stories about the war at that time. only one out of all have a date, 1943. Pretty interesting but i know nothing about them. Hope someone can give some advice. thank you