Long Buried Treasure - Found!

This afternoon, my brother sent me a text, saying "Found these stuck to the wall of Mom's garage."  Attached was this picture:

"These," of course, would be my first edition Gamma World rulebook and a Top Secret GM's screen.  He said, it's not just the covers, but there's actual content left.  How they ended up where he found them is anyone's guess, (I'm guessing they ended up on a shelf with a bunch of magazines and then slipped behind it) but Mom is dropping them in the mail for me and I'm anxious to see what, if anything survived.