BibTeX:
@incollection{Various,
  author = {Various},
  title = {Shoghi Effendi on the Tennis Court},
  booktitle = {bahaistories.com archive},
  url = {https://bahaistories.com/subject/exercise},
}

APA:
Various. Shoghi Effendi on the Tennis Court. In *bahaistories.com archive*.

MLA:
Various. "Shoghi Effendi on the Tennis Court." *bahaistories.com archive*, n.d..

Chicago:
Various. "Shoghi Effendi on the Tennis Court." In *bahaistories.com archive*, n.d..