BibTeX:
@incollection{Various,
  author = {Various},
  title = {Mother met ‘Abdu’l-Bahá in 1912, when she was 15 years old},
  booktitle = {bahaistories.com archive},
  url = {https://bahaistories.com/subject/timing},
}

APA:
Various. Mother met ‘Abdu’l-Bahá in 1912, when she was 15 years old. In *bahaistories.com archive*.

MLA:
Various. "Mother met ‘Abdu’l-Bahá in 1912, when she was 15 years old." *bahaistories.com archive*, n.d..

Chicago:
Various. "Mother met ‘Abdu’l-Bahá in 1912, when she was 15 years old." In *bahaistories.com archive*, n.d..