BibTeX:
@incollection{AbdulBah1982,
  author = {'Abdu'l-Bahá},
  title = {O Thou My Loving, My Deeply Spiritual Sister!},
  booktitle = {Bahíyyih Khánum},
  year = {1982},
  url = {https://www.gutenberg.org/cache/epub/19242/pg19242-images.html},
}

APA:
'Abdu'l-Bahá. (1982). O Thou My Loving, My Deeply Spiritual Sister!. In *Bahíyyih Khánum*.

MLA:
'Abdu'l-Bahá. "O Thou My Loving, My Deeply Spiritual Sister!." *Bahíyyih Khánum*, 1982.

Chicago:
'Abdu'l-Bahá. "O Thou My Loving, My Deeply Spiritual Sister!." In *Bahíyyih Khánum*, 1982.