If a work (probably an e-book, could be an article) doesn't have page numbers but does label chapters and sections...
MLA
Assuming that the sections are officially numbered... use the "sec." abbreviation.
- E,g, (Smith ch. 6, sec. 2).
MLA style does not want you to manually count or number things if the source hasn't provided that info.
APA
You'll name the section in your parenthetical citation. If the heading or section name is lengthy, you can abbreviate it. Include the word "section" after the name.
- e.g. (Smith, 2009, Kuiper Belt section).
APA does, we're afraid, encourage you to manually count paragraphs, if it will help. In a lengthy section, you could combine both the section and paragraph info.
- e.g. (Smith, 2015, Oort Cloud section, para. 7).
