BibTeX:
@incollection{BahChronicleseditors,
  author = {Bahá'í Chronicles editors},
  title = {The King and the Beloved of Martyrs},
  booktitle = {Bahá'í Chronicles},
  url = {https://bahaichronicles.org/mirza-muhammad-husayn-and-mirza-muhammad-hasan/},
}

APA:
Bahá'í Chronicles editors. The King and the Beloved of Martyrs. In *Bahá'í Chronicles*.

MLA:
Bahá'í Chronicles editors. "The King and the Beloved of Martyrs." *Bahá'í Chronicles*, n.d..

Chicago:
Bahá'í Chronicles editors. "The King and the Beloved of Martyrs." In *Bahá'í Chronicles*, n.d..