Pre-War book (Fallout: New Vegas)

A Pre-War Book is a book that has not been destroyed. It is a fairly rare item, desired by the Capital Wasteland Brotherhood of Steel. Specifically, the Brotherhood Scribe Yearling, located within the Arlington Library, will reward you with 10 XP and 100 bottle caps per book for contributing these to their archives. See Yearning for Learning.

Note
Crazy Wolfgang and a few other vendors may sell "false" Pre-War Books. Once you fully invest in his inventory, Wolfgang will begin to carry them. Books that can be turned in have a value of 1, a green cover, and show a special "Book" icon, while Wolfgang's books have a value of 5, a blue cover, and appear with the "Junk" icon in your inventory. These "false" Pre-War Books can be found throughout the wasteland and Point Lookout as well.

Carrying more than 99 pre-war books and telling Scribe Yearling 'just take all the books I have' will cause her to take only 99 books, yet give you caps and xp for all the books you carry. For example, carrying 110 pre-war books and giving them all to the scribe leaves you with 1100 xp, 11000 caps and 11 books left.

Locations
G.E.C.K. shows that there are 111 Pre-War Books ("BookGeneric01") in the game, more may be added with DLC. The links below often tell you where to find them: