BibTeX:
@incollection{BahChronicleseditors,
  author = {Bahá'í Chronicles editors},
  title = {Louis George Gregory},
  booktitle = {Bahá'í Chronicles},
  url = {https://bahaichronicles.org/louis-george-gregory/},
}

APA:
Bahá'í Chronicles editors. Louis George Gregory. In *Bahá'í Chronicles*.

MLA:
Bahá'í Chronicles editors. "Louis George Gregory." *Bahá'í Chronicles*, n.d..

Chicago:
Bahá'í Chronicles editors. "Louis George Gregory." In *Bahá'í Chronicles*, n.d..