Reddit mentions of `Abdu'l-Bahá: The Centre of the Covenant of Bahá'u'lláh

See https://bahaipedia.org/%E2%80%98Abdu%E2%80%99l-Bah%C3%A1 which includes a short biography and lists some books discussing 'Abdu'l-Baha's life or specific experiences about Him, such as personal experiences of early Baha'is (in the West in English) and His travels in Europe or North America ( https://www.amazon.com/Abdul-Baha-Their-Midst-Earl-Redman-ebook/dp/B006BBMQIQ is a book about 'Abdu'l-Baha's travels in Europe and North America from 1911 and 1913 told from the perspectives of reports and reactions from people who met and witnessed Him).

*There is an older history text by Hasan Balyuzi https://www.amazon.com/%60Abdul-Bah%C3%A1-Covenant-Bah%C3%A1ull%C3%A1h-H-Balyuzi/dp/0853980292 that is widely regarded (and may be available in pdf form for free which is sometimes the case with older Baha'i texts or found relatively cheaply in paperback and used on Amazon).

* Mary Perkins wrote a more recent biography of 'Abdu'l-Baha that is popular and well read (easier to read). A link to a reference is at https://www.barnesandnoble.com/w/servant-of-the-glory-mary-perkins/1115883806 .(Also available on Amazon and other sites and from Baha'i book stores.).

Shoghi Effendi discusses the life of 'Abdu'l-Baha in God Passes By, which is available for free download online. The third section of the book, eight chapters, covers the ministry of 'Abdu'l-Baha from 1892 to 1921. https://www.bahai.org/library/authoritative-texts/shoghi-effendi/god-passes-by/ It is a fairly densely written text (Shoghi Effendi often wrote precisely and with sometimes long sentences.), so you really have to take time to read it.

Vignettes from the Life of 'Abdu'l-Baha is a book of short stories about 'Abdu'l-Baha (during His ministry mostly) that, while many are not authoritative ("pilgrim's notes"), are very instructive and inspiring and organized around various themes to illustrate His life and actions as an Exemplar. https://www.amazon.com/Vignettes-Life-Abdul-Baha-Honnold-Annamarie/dp/0853981299 (Must be out of print, because some listed prices seemed a bit high but used prices are more reasonable.)

Afroukhteh, Youness (2003) [1952], Memories of Nine Years in 'Akká, Oxford, UK: George Ronald, ISBN 0-85398-477-8 is book I enjoyed.

Dr. Stockman has a really good book on 'Abdu'l-Baha's travels in North America in 1912. https://www.amazon.com/Abdul-Baha-America-Robert-H-Stockman/dp/1931847975