How do I go about getting the exact date something was written inside of a book?

Question: How do I go about getting the exact date something was written inside of a book!? (in pencil)!?
Best Answer - Chosen by Asker:

do you mean like testing the pencil markings to see how old they are!?

you'd have to be able to analyze how much of the marking is still there, and know the half-life of graphite!.

Really this question ought to be posed to chemists!.Www@QuestionHome@Com