BibTeX:
@incollection{Various,
  author = {Various},
  title = {How Ṭáhirih Found the Báb},
  booktitle = {Baha'i Stories for Children},
  url = {https://bahaistoriesforchildren.blogspot.com/2016/03/tahirih-only-woman-letter-of-living.html},
}

APA:
Various. How Ṭáhirih Found the Báb. In *Baha'i Stories for Children*.

MLA:
Various. "How Ṭáhirih Found the Báb." *Baha'i Stories for Children*, n.d..

Chicago:
Various. "How Ṭáhirih Found the Báb." In *Baha'i Stories for Children*, n.d..