Primary sources were either created during the time period being studied or were created at a later date by a participant in the events being studied (as in the case of memoirs). They reflect the individual viewpoint of a participant or observer. Primary sources enable the researcher to get as close as possible to what actually happened during an historical event or time period; some types of primary sources might be historical magazines or newspapers, diaries or journals, old photographs, interviews, letters, and more. A secondary source is a work that interprets or analyzes an historical event or phenomenon. It is generally at least one step removed from the event and is often based on primary sources. Examples include: scholarly or popular books and articles, reference books, and textbooks.