"Primary sources are the evidence of history, original records or objects created by participants or observers at the time historical events occurred or even well after events, as in memoirs and oral histories."
Source: Primary Sources on the Web: Finding, Evaluating, Using by the American Library Association
Types of primary sources:
"Any published or unpublished work that is one step removed from the original source, usually describing, summarizing, analyzing, evaluating, derived from, or based on primary source materials"
Source: Dictionary for Library and Information Science
Types of secondary sources: