BibTeX:
@incollection{Various,
  author = {Various},
  title = {Louis Gregory at the Washington Luncheon},
  booktitle = {bahaistories.com archive},
  url = {https://bahaistories.com/subject/race-unity},
}

APA:
Various. Louis Gregory at the Washington Luncheon. In *bahaistories.com archive*.

MLA:
Various. "Louis Gregory at the Washington Luncheon." *bahaistories.com archive*, n.d..

Chicago:
Various. "Louis Gregory at the Washington Luncheon." In *bahaistories.com archive*, n.d..