Primary and secondary sources. Primary sources provide firsthand knowledge, while secondary sources report on or analyze the research of others. Primary sources are basic sources of raw information, including your own field research; films, works of art, or other objects you examine; literary works you read; and eyewitness accounts, photographs, news reports, and historical documents (such as letters and speeches). Secondary sources are descriptions or interpretations of primary sources, such as researchers’ reports, reviews, biographies, and encyclopedia articles. Often what constitutes a primary or secondary source depends on the purpose of your research. A critic’s evaluation of a film, for instance, serves as a secondary source if you are writing about the film but as a primary source if you are studying the critic’s writing.