Don't bother with anything after 1976.
Here was a really good issue - June of 61. Look at the list of articles to the right - the only hanging for mutiny in the U.S. Navy, the surrender at Appomattox, Frank Merriwell the dime novel hero, Catherwood the discoverer of the Mayan civilization, Yalta, the first New York subway (run by compressed air!), and funny money issued during the Depression.
It is just a real shame that the pictures aren't reproduced -- you don't realize how integral they are to the articles until they are missing! It's obvious that they scanned the articles in, because there are lots of typos, too.
But almost any college or university library should have a full set of these things.