In a source that does not number annotations, the notes section may list notes by their relevant main-text page number. Cite such notes by providing the number of the page in the notes section where they appear.
A notes section by the author of the annotated work can be cited like any other text from the work:
According to Michael Sims, White “was fully aware of the ancient pastoral themes” in Charlotte’s Web “and even referred to the book as a ‘paean,’ the ancient Greek word for a hymn of praise” (279).
Work Cited
Sims, Michael. The Story of Charlotte’s Web: E. B. White’s Eccentric Life in Nature and the Birth of an American Classic. Walker, 2011.
Notes by another contributor can be cited by creating an entry for the notes section:
Terry Castle describes the letter-writing technique of “crossing” in her notes to Emma (442).
Work Cited
Castle, Terry. Explanatory notes. Emma, by Jane Austen, edited by James Kinsley, Oxford UP, 1995, pp. 441–45.
In unpaginated sources, such as e-books, cite the notes section as you would cite a chapter:
According to Michael Sims, White “was fully aware of the ancient pastoral themes” in Charlotte’s Web “and even referred to the book as a ‘paean,’ the ancient Greek word for a hymn of praise” (Notes).
Terry Castle describes the letter-writing technique of “crossing” in her notes to Emma (Explanatory notes).
Additional ways of citing notes by contributors can be found here.