This is not everyone. In fact, it is rather brief. It will give you a place to start your search. The constant research and attempts to understand the past puts the Reenactor in close personal contact with the writings and thoughts of the Framers of the Nation. Books, newspaper accounts, court records, journals, diaries and letters, written at the time, are the standard reference materials that are used.
Secondary sources are later research that is based on primary sources.
An example would be a diary of your Great-grandfather during the Gold Rush days as a primary resource, while the secondary source would be the family legend of his exploits as told by someone else and written down by Aunt Edna for her genealogy records. Back during the forming of this Nation, politics were a major interest, as it is now. Many discussions took place, letters were written, speeches made and public discourse recorded. Reading the primary sources, it often seems as though they are fiction when contrasted against the present day. The intent is very clear.