Knowing the different types of primary sources will help you evaluate the reliability of primary sources. Some primary sources are published documents. They were created for large audiences and were distributed widely. Published documents include books, magazines, newspapers, government documents, non-government reports, literature of all kinds, advertisements, maps, pamphlets, posters, laws, and court decisions. When reviewing published documents, remember that just because something was published does not make it truthful, accurate, or reliable.
Every document has a creator, and every creator has a point of view, blind spots, and biases.
Also remember that even biased and opinionated sources can tell us important things about the past. Many types of unpublished documents have been saved, and can be used as primary sources. These include personal letters, diaries, journals, wills, deeds, family Bibles containing family histories, school report cards, and many other sources. Unpublished business records such as correspondence, financial ledgers, information about customers, board meeting minutes, and research and development files also give clues about the past. Unpublished documents often come from community organisations, churches, service clubs, political parties, and labour unions in the form of membership lists, meeting minutes, speeches, financial and other records.