Any Idea On Where This Is From ?

Wow! Library books with free samples!

On a more serious side, they may have sentimental value to their original owner, even if the monetary value is low. If you haven't already, you might consider telling the library you found them there when you return the book, just in case whoever put them there comes back for them.

To elaborate on what kuhli said, this one is from the German Empire, issued sometime before WWI (you'll find the date on the front of the note, around the middle - I can't quite read it from your pics. If kuhli is correct with his Pick catalogue number (and if Pick hasn't renumbered Germany between his book and mine) then the date should be 2nd February 1908.

100 marks sounds like a lot (and back in the early 1900's, it was a lot - around US$20), but Germany losing WWI caused severe inflation which made the Imperial mark worthless. Perfectly flat, undamaged specimens are worth quite a bit, but being such a large note they were rarely kept that way.

My catalogue is way out of date, but I'd guess a value around $5 for that one.

The actual date Berlin 7 February 1908 not the 2nd.
Would that make sense?

The first note was issued in the Phillipines by the Japanese Occupation Government, later on the holders of the note tried to sue the US and new Phillipine Government to force them to payout on these notes, the holders submitted them to some organisation which stamped them with these purple hand stamps. Subsequently they of course lost the lawsuit and the notes were released to the collecting community sometime beginning in the 1960's.

I admit, I have found notes in my banknote catalogs too, I placed them in there when I was looking them up, got sidetracked and found them a long time later. Recently I found a 1963-A $1 bill in a catalog that must have been there for at least 5 years.