BibTeX:
@incollection{JulietThompson,
  author = {Juliet Thompson},
  title = {Letters Shower as Rain},
  booktitle = {The Diary of Juliet Thompson},
}

APA:
Juliet Thompson. Letters Shower as Rain. In *The Diary of Juliet Thompson*.

MLA:
Juliet Thompson. "Letters Shower as Rain." *The Diary of Juliet Thompson*, n.d..

Chicago:
Juliet Thompson. "Letters Shower as Rain." In *The Diary of Juliet Thompson*, n.d..