It seems kind of obvious I know but seriously - document everything. Not only should you document it as if you were writing a paper (/wipes away memories of college thesis papers), but also note where you found the item. Did you find it at the public library? If so was it in a collection or on the shelves? What is the call number? Did you find it in a courthouse? If so, which one? What department? Did a family member provide you the information? By adding this information, you will know where to go back to if you ever should have to do so!