BibTeX:
@incollection{NabliAam1932,
  author = {Nabíl-i-A'ẓam},
  title = {The Black Pit: Bahá'u'lláh in the Síyáh-Chál},
  booktitle = {The Dawn-Breakers: Nabíl's Narrative of the Early Days of the Bahá'í Revelation},
  year = {1932},
  publisher = {Bahá'í Publishing Trust},
  url = {https://www.bahai.org/library/other-literature/historical/dawn-breakers/},
}

APA:
Nabíl-i-A'ẓam. (1932). The Black Pit: Bahá'u'lláh in the Síyáh-Chál. In *The Dawn-Breakers: Nabíl's Narrative of the Early Days of the Bahá'í Revelation*. Bahá'í Publishing Trust.

MLA:
Nabíl-i-A'ẓam. "The Black Pit: Bahá'u'lláh in the Síyáh-Chál." *The Dawn-Breakers: Nabíl's Narrative of the Early Days of the Bahá'í Revelation*, Bahá'í Publishing Trust, 1932.

Chicago:
Nabíl-i-A'ẓam. "The Black Pit: Bahá'u'lláh in the Síyáh-Chál." In *The Dawn-Breakers: Nabíl's Narrative of the Early Days of the Bahá'í Revelation*, Bahá'í Publishing Trust, 1932.