I found this book about Shi’a Islam, by Sayyid Moustafa Al-Qazwini. One of the chapters I found Particularly interesting was the one titled “The Five Schools of Islamic Thought,” which briefly highlights the histories of the five major schools in Islam.
https://www.al-islam.org/inquiries-about-shia-islam-sayyid-moustafa-al-qazwini/five-schools-islamic-thought
Author: cfeindt2
This article introduces the history of Ibadism, in its first few paragraphs. Then discusses the beliefs of Ibadis and compares and contrasts them to the practices of Sunnis and Shi’ites. The rest of the article largely focuses on Ibadis in Oman and Zanzibar.