BibTeX:
@incollection{MrzMamdiZarqn1998,
  author = {Mírzá Maḥmúd-i-Zarqání},
  title = {An Unprepared Talk for an Admiral: 'Abdu'l-Bahá and Robert Peary},
  booktitle = {Mahmúd's Diary: The Diary of Mírzá Maḥmúd-i-Zarqání},
  year = {1998},
  publisher = {George Ronald},
}

APA:
Mírzá Maḥmúd-i-Zarqání. (1998). An Unprepared Talk for an Admiral: 'Abdu'l-Bahá and Robert Peary. In *Mahmúd's Diary: The Diary of Mírzá Maḥmúd-i-Zarqání*. George Ronald.

MLA:
Mírzá Maḥmúd-i-Zarqání. "An Unprepared Talk for an Admiral: 'Abdu'l-Bahá and Robert Peary." *Mahmúd's Diary: The Diary of Mírzá Maḥmúd-i-Zarqání*, George Ronald, 1998.

Chicago:
Mírzá Maḥmúd-i-Zarqání. "An Unprepared Talk for an Admiral: 'Abdu'l-Bahá and Robert Peary." In *Mahmúd's Diary: The Diary of Mírzá Maḥmúd-i-Zarqání*, George Ronald, 1998.