Well, the calendar page is most likely June, 1967. June of 1967 starts on a Thursday, which would make the red 14 on the page Flag Day. The previous month, as seen here, shows day 30 as red, making it Memorial Day (which, prior to 1971, was observed on May 30.) The calendar artwork looks familiar but I can't place it. And an amendment to my earlier list; January also follows a 31 day month.