You may also find formally published archival sources available in published, edited collections or sourcebooks/document collections.
For example, some authors will have published correspondence selected from archives.
Other relevant terms that may appear in subjects are: biographies, diaries, documents, sources, etc.

Full-text, searchable scans of source material of all types from the 17th and 18th centuries; an important resource for primary information about every aspect of life in 17th- and 18th-century America.
Scans of over 200,000 volumes published in English (mainly in the UK) in the 18th century, based on the English Short Title Catalogue. Dates of Coverage: 1701 to 1800. Part of Gale Primary Sources.
Topically focused collections of historical documents, including the American Civil Liberties Union Papers (1912-1990), Archives Unbound, Archives of Sexuality & Gender, British Library Newspapers, The Economist Historical Archive (1843-2014), 18th Century Collections Online, Indigenous Peoples: North America, 19th Century Collections Online, 19th Century U.S. Newspapers, Political Radicalism & Extremism in the 20th Century, Sabin Americana (1500-1926), and The London Times Digital Archive (1785-1985).
National and regional English, Scottish, Irish and Welsh. Stengths include coverage include political and social movements such as Reform, Chartism, and Home Rule, and penny papers aimed at the working and clerical classes. Dates of Coverage: 1800s. Part of Gale Primary Sources.
Full text searchable articles representing most US states. Includes searchable page scans of the originals. Part of Gale Primary Sources. Dates of Coverage: 1800-1899
Indexing of articles in historical American popular magazines of all types.