BibTeX:
@incollection{Various,
  author = {Various},
  title = {Tammy and the Butterfly},
  booktitle = {Baha'i Stories for Children},
  url = {https://bahaistoriesforchildren.blogspot.com/2020/09/tammy-and-butterfly.html},
}

APA:
Various. Tammy and the Butterfly. In *Baha'i Stories for Children*.

MLA:
Various. "Tammy and the Butterfly." *Baha'i Stories for Children*, n.d..

Chicago:
Various. "Tammy and the Butterfly." In *Baha'i Stories for Children*, n.d..