BibTeX:
@incollection{AbdulBah1943,
  author = {'Abdu'l-Bahá},
  title = {Mankind Is in Danger},
  booktitle = {Bahá'í World Faith},
  year = {1943},
  url = {https://www.gutenberg.org/cache/epub/19239/pg19239-images.html},
}

APA:
'Abdu'l-Bahá. (1943). Mankind Is in Danger. In *Bahá'í World Faith*.

MLA:
'Abdu'l-Bahá. "Mankind Is in Danger." *Bahá'í World Faith*, 1943.

Chicago:
'Abdu'l-Bahá. "Mankind Is in Danger." In *Bahá'í World Faith*, 1943.