I am dying to find a copy of a book I had when I was younger. It must have been published no later than the early-mid-1980s.  It was an oversized, softcover book and I remember a light blue cover.  It was a really cool book which had on each page a scientific mystery, unsolved crime, unproven theory, etc....such as "Who built the statues on Easter Island?" or "What happened to the Lost Colony?".....I think each page had the question at the top and then the text of the page explained what was known, with some drawings scattered within the text.  The pages were like that recycled-looking grayish paper rather than stark white pages.

I have no clue what the title was or how to find it!!!  If I try a search on Amazon with "unsolved mysteries" or "questions" I get tens of thousands of hits.

If anyone knows of this book or of a better way to search for it, please post!  Thanks so much!

You may want to check with a librarian or someone at a bookstore.  They seem to know all the books!

Edit:  Could this be the one?  Encyclopedia Browns Third Record Book of Weird and Wonderful Facts 

You can also put that description in at abebooks.com.  Thanks to a helpful member here at PBS I found a book my husband read 15 years ago and couldn't remember the name of.  I even put in an incorrect description and someone there found the right book for me.

Also try Loganberrybooks.com - they specialize in childrens books.

Thanks so much for all the hints!  Margie: I don't think that's the one.  I tried searching at alibris.com but will try the others you all suggested.