BibTeX:
@incollection{OnbehalfofShoghiEffendi1982,
  author = {On behalf of Shoghi Effendi},
  title = {Months of Mourning},
  booktitle = {Bahíyyih Khánum},
  year = {1982},
  pages = {Part IV, no. 26},
  url = {https://www.gutenberg.org/cache/epub/19242/pg19242-images.html},
}

APA:
On behalf of Shoghi Effendi. (1982). Months of Mourning. In *Bahíyyih Khánum* (p. Part IV, no. 26).

MLA:
On behalf of Shoghi Effendi. "Months of Mourning." *Bahíyyih Khánum*, 1982, p. Part IV, no. 26.

Chicago:
On behalf of Shoghi Effendi. "Months of Mourning." In *Bahíyyih Khánum*, Part IV, no. 26. 1982.