Ilmu, Peradaban, dan Guru Swasta

https://www.researchgate.net/publication/303179563_The_Effective_Reasons_for_ the_Rise_and_fall_of_Abbasids_State

https://www.worldhistory.org/article/1387/cats-in-the-middle-ages/

Salam, Abdus (1994). Renaissance of Sciences in Islamic Countries. p. 9. ISBN 978-9971-5-0946-0