WITNESS

ʿAmal al-musabbaʿ fī al-dāʾirah wa-qismat al-zāwiyah al-mustaqīmah al-khaṭṭayn bi-thalāthah aqsām mutasāwiyyah_Cairo_Dār al-kutub_Muṣṭafā Fāḍil riyāḍa_41