BibTeX:
@incollection{BahChronicleseditors,
  author = {Bahá'í Chronicles editors},
  title = {Mírzá Maḥmúd and His Diary},
  booktitle = {Bahá'í Chronicles},
  url = {https://bahaichronicles.org/mirza-mahmud-i-zargani/},
}

APA:
Bahá'í Chronicles editors. Mírzá Maḥmúd and His Diary. In *Bahá'í Chronicles*.

MLA:
Bahá'í Chronicles editors. "Mírzá Maḥmúd and His Diary." *Bahá'í Chronicles*, n.d..

Chicago:
Bahá'í Chronicles editors. "Mírzá Maḥmúd and His Diary." In *Bahá'í Chronicles*, n.d..