BibTeX:
@incollection{Various,
  author = {Various},
  title = {Wear a Happy Face},
  booktitle = {bahaistories.com archive},
  url = {https://bahaistories.com/subject/happiness},
}

APA:
Various. Wear a Happy Face. In *bahaistories.com archive*.

MLA:
Various. "Wear a Happy Face." *bahaistories.com archive*, n.d..

Chicago:
Various. "Wear a Happy Face." In *bahaistories.com archive*, n.d..