Roughly speaking, primary sources are pieces of ‘evidence’ dating from the period you are investigating, for example William the Silent’s Apology, the Proceedings of the Dutch States-General or the literal text of a treaty. The distinction between secondary and primary sources is not always clear, as books can function as primary sources in academic research.

Primary sources are mainly defined as:

• personal documents (journals, letters, memoirs, autobiographies, speeches, interviews, photographs, etc.)
• official documents (government documents, statistics, corporate records, etc.)
• art (poetry, music, paintings, film, literature, etc.)
• material culture (clothing, tools, buildings, toys, vehicles, monuments, etc.)
• news media (newspapers, magazines, pamphlets, posters, etc.)

Primary sources are usually kept in archives, but there are collections of sources too: books or websites that have collected sources about a particular topic or from one particular medium, such as an out-of-print newspaper. Another helpful tool is a directory listing source locations. Directories are a good place to find out where particular sources are stored. Say, for instance, that you wanted to track down sources on the history of the Dutch East Indies. You could consult the ‘Directory of sources present in the Netherlands on the history of the Dutch East Indies/Indonesia, 1816-1942’. To locate these sources, you could consult compendiums, registers and directories of archives. It should be noted, however, that the Internet has made such directories less crucial for finding archival material.

In order to correctly use certain sources (e.g. archeological finds, old writing systems, coins, calendars, statistical data), you should use what are known as the auxiliary sciences of history, such as archeology and statistics.