Every profession has tools that are practically indispensable.
For me, one of those tools is a book I use almost daily. It is Bulletin 70, Fossils of Ohio, published by the state Department of Natural Resources' Division of Geological Survey. A very enjoyable part of my job here at the Orton Geological Museum is identifying rocks, minerals and fossils for members of the public. Often the fossils they bring in are fragmentary. I can almost always count on Bulletin 70 to have a photo of a good, or at least a more complete, specimen.