One potentially confusing citation is for a chapter of a book. Some books are compliations of essays or articles written by different authors under the direction of an editor. Here is an example of a citation which is a chapter of a book (in APA style):
Where it can get confusing is that there are two titles listed, just like a citation for a periodical. The first title is for the name of the essay or article and the second is for the book title.
The clues that let you know that this is not a periodical are
1) the presence of publication place and publisher information, which is only used for books,
2) the fact that the book has editors and
3) in some citation styles, the author and title are found "In" the larger work represented by the book title.
