I love Little Golden Books, Wonder Books, Junior Elf Books, etc. If I could make a living selling nothing but these books I would! They were little thin hardcovers that were very popular during the baby boomer years. During my childhood I remember buying these as Woolworth and McCrory's -- how are those for store names from the past?
LGBs from the 1940's through early 1960's had an edition letter at the gutter of the last page of the book. If you have an LGB published in the 1940's, 1950's, or early 1960's, open the book to the last page. Look down at the very bottom of the page. (You may have to lift the binding at bottom of page very slightly to see this.) With older LGBs you will see a letter there. "A" signifies a First Edition, "B" is a Second Edition, "C" is a Third Edition, etc.
I collect LGBs and am attaching pictures of a couple of books from my personal collection. Cleo is the story of a very cute Basset Hound dog who is a television star. Christmas Manger is a LGB activity book -- you can construct a Christmas Manager by cutting and assembling the pages of this book. I am also including a photo of the last page of these books. You'll see the tiny letter "A" at the very bottom of the page. (You may need to zoom in to see it.)