BibTeX:
@incollection{Various,
  author = {Various},
  title = {This is my letter to the editor which was published in the McMinnville, Oregon},
  booktitle = {bahaistories.com archive},
  url = {https://bahaistories.com/subject/underground-railway},
}

APA:
Various. This is my letter to the editor which was published in the McMinnville, Oregon. In *bahaistories.com archive*.

MLA:
Various. "This is my letter to the editor which was published in the McMinnville, Oregon." *bahaistories.com archive*, n.d..

Chicago:
Various. "This is my letter to the editor which was published in the McMinnville, Oregon." In *bahaistories.com archive*, n.d..