BibTeX:
@incollection{BahChronicleseditors,
  author = {Bahá'í Chronicles editors},
  title = {The Keeper of the Door},
  booktitle = {Bahá'í Chronicles},
  url = {https://bahaichronicles.org/ismullahul-asdaq-mulla-%e1%b9%a3adiq/},
}

APA:
Bahá'í Chronicles editors. The Keeper of the Door. In *Bahá'í Chronicles*.

MLA:
Bahá'í Chronicles editors. "The Keeper of the Door." *Bahá'í Chronicles*, n.d..

Chicago:
Bahá'í Chronicles editors. "The Keeper of the Door." In *Bahá'í Chronicles*, n.d..