Most likely you're seeing an old MLA citation or a current Chicago citation that's using "n.p." for "no publisher" or "no place of publication," depending on the citation style and where it's placed.
- Chicago 17th edition [current, as of 2023] still allows for n.p. to mean "no publisher," "no place," or "no page."
- MLA 7th edition [obsolete] used this protocol, but it was dropped in later versions [current version is 9th, as of 2023] in favor of simply skipping over missing info. Place of publication has been removed entirely as a necessary piece of the citation.
- Example of no place: N.p.: U of Gotham P, 2008.
- Example of no publisher: New York: n.p., 2008.
