BibTeX:
@incollection{MrzMamdiZarqn1998,
  author = {Mírzá Maḥmúd-i-Zarqání},
  title = {An Evening with the Syrians: 'Abdu'l-Bahá in Lower Manhattan},
  booktitle = {Mahmúd's Diary: The Diary of Mírzá Maḥmúd-i-Zarqání},
  year = {1998},
  publisher = {George Ronald},
}

APA:
Mírzá Maḥmúd-i-Zarqání. (1998). An Evening with the Syrians: 'Abdu'l-Bahá in Lower Manhattan. In *Mahmúd's Diary: The Diary of Mírzá Maḥmúd-i-Zarqání*. George Ronald.

MLA:
Mírzá Maḥmúd-i-Zarqání. "An Evening with the Syrians: 'Abdu'l-Bahá in Lower Manhattan." *Mahmúd's Diary: The Diary of Mírzá Maḥmúd-i-Zarqání*, George Ronald, 1998.

Chicago:
Mírzá Maḥmúd-i-Zarqání. "An Evening with the Syrians: 'Abdu'l-Bahá in Lower Manhattan." In *Mahmúd's Diary: The Diary of Mírzá Maḥmúd-i-Zarqání*, George Ronald, 1998.