BibTeX:
@incollection{BahChronicleseditors,
  author = {Bahá'í Chronicles editors},
  title = {John Esslemont: A Doctor at the Master's Side},
  booktitle = {Bahá'í Chronicles},
  url = {https://bahaichronicles.org/john-esslemont/},
}

APA:
Bahá'í Chronicles editors. John Esslemont: A Doctor at the Master's Side. In *Bahá'í Chronicles*.

MLA:
Bahá'í Chronicles editors. "John Esslemont: A Doctor at the Master's Side." *Bahá'í Chronicles*, n.d..

Chicago:
Bahá'í Chronicles editors. "John Esslemont: A Doctor at the Master's Side." In *Bahá'í Chronicles*, n.d..