The purpose of a citation is to tell someone else where you found a certain piece of information. Archival materials are unique and the original can only be found in one place. Even published materials in special collections can be hard to find in more than one repository, so a good citation to the copy you used is important. Citations for archival materials and rare or unusual published materials should make it clear not only what the source is, but also where, exactly, it can be found.
Primary source citation depends on the type of primary source you are using (i.e. a law document, newspaper, etc...) and the style of citation required (i.e. MLA, APA, etc...).
Primary sources are firsthand, contemporary accounts of events created by individuals during that period of time or several years later (such as correspondence, diaries, memoirs and personal histories). These original records can be found in several media such as print, artwork, and audio and visual recording. Examples of primary sources include manuscripts, newspapers, speeches, cartoons, photographs, video, and artifacts. Primary sources can be described as those sources that are closest to the origin of the information. They contain raw information and thus, must be interpreted by researchers.
Secondary sources are closely related to primary sources and often interpret them. These sources are documents that relate to information that originated elsewhere. Secondary sources often use generalizations, analysis, interpretation, and synthesis of primary sources. Examples of secondary sources include textbooks, articles, and reference books.