Your research may takes many forms. From treasure maps ( not many of then around) to news papers. Another good area is the older people that live in the area you are working in. They can tell many things that is not in the history books.
Their are many treasures that you can go after. I always said that's why Michigan has winters, so you can research.
There are many things you can look up in books, news papers, diary's, insurance reports, and private and public records. As many places that there are to look, there are more things to look for, such as shipwrecks, criminal action, recluses, old trails, historic sites, ghost towns, robberies, old settlement camps and gold deposits.
You will always need a map. Maps new or old will help you to where you want to go. You should never turn down a free map, even if you think you will never go there, you may need it some day.
I have many old treasure magazines, some over 40 years old, that I am selling for $5.00 each. I may have the one you are looking for.