Al-Kharaj wa Sina'at al-Kitaba (The Land Tax and the Craft of the Secretary)
A guide for the secretaries of the government offices, written by Qudama ibn Jafar (d. 337 AH). It covers the system of government offices, the land tax, the postal service, the routes and the revenues of the Abbasid state, and is an important source for financial administration and administrative geography.
Qudama ibn Jafar