BibTeX:
@incollection{Various,
  author = {Various},
  title = {A Declaration in the Garden Tent},
  booktitle = {bahaistories.com archive},
  url = {https://bahaistories.com/subject/ridvan-ninth-day},
}

APA:
Various. A Declaration in the Garden Tent. In *bahaistories.com archive*.

MLA:
Various. "A Declaration in the Garden Tent." *bahaistories.com archive*, n.d..

Chicago:
Various. "A Declaration in the Garden Tent." In *bahaistories.com archive*, n.d..