BibTeX:
@incollection{Various,
  author = {Various},
  title = {A Love Letter to the Friends in Germany},
  booktitle = {bahaistories.com archive},
  url = {https://bahaistories.com/subject/teaching},
}

APA:
Various. A Love Letter to the Friends in Germany. In *bahaistories.com archive*.

MLA:
Various. "A Love Letter to the Friends in Germany." *bahaistories.com archive*, n.d..

Chicago:
Various. "A Love Letter to the Friends in Germany." In *bahaistories.com archive*, n.d..