Published primary works can include diaries, collections of letters (correspondence), memoirs and autobiography.
To help identify possible primary sources in the UNH library catalog or WorldCat, use one of the following terms in the subject field along with the subject/topic/person:
For example: the subject "Eisenhower, Dwight D (Dwight David) 1890-1969 - Correspondence" retrieves
There is a broader subject heading: Presidents -- United States -- Correspondence