Historians distinguish between primary vs. secondary sources. 
"Secondary" is fairly straightforward to define: what historians write about past phenomena. The best known examples are books and journal articles. Other formats can include papers in edited volumes, chapters, dissertations, and more.
"Primary" sources however take many forms--correspondence, diaries, personal narratives, official public records, news reports, advertisements... Primary sources are usually contemporary with the past phenomena under study.
It is important to remember that primary sources may be reproduced and published much later. Even if you are looking at a copy, it is still a primary source.
Mending the Family Kettle. Photograph. Retrieved from the Library of Congress
<www.loc.gov/item/2001696151/>.
MLA resources typically use MLA Style The MLA website provides examples of how to cite and how to structure a paper in this style.
MLA follows this format:
Article Resource
Lastname, Firstname. "Title of Article." Journal Title, vol. X, no. X, Date, pp. X-X. Database, https://doi.org/XXXXXXX OR URL.
The library can guide you to citation management software and resources to help you properly cite your sources.
