Letters, diaries, journal entries, public records as well as contemporaneous newspapers articles offer solid examples of this type of primary source. Fictional works such as short stories or novels written during that specific time period constitute primary documents, too.
Primary sources are actual records that have survived from the past, such as letters, photographs, articles of clothing. Secondary sources are accounts of the past created by people writing about events sometime after they happened. For example, your history textbook is a secondary source.
