Mccarus, Ernest Nasseph (1958). A Kurdish Grammar: Descriptive Analysis of the Kurdish of Sulaimaniya, Iraq. American Council of Learned Societies. p.6.
The Political and Dynastic History of the Iranic World, C.E. Bosworth, The Cambridge History of Iran:The Saljuq and Mongol Period, Vol. 5, ed. J.A. Boyle, (Cambridge University Press, 1968), 95.
F. Daftary, "Intellectual Traditions in Islam", I.B.Tauris, 2001. pg 147: "But the origins of the family of Shaykh Safi al-Din go back not to Hijaz but to Kurdistan, from where, seven generations before him, Firuz Shah Zarin-kulah had migrated to Azerbaijan"
Runciman S. Hunyadi Z., Laszlovszky J., The Crusades and the Military Orders: Expanding the Frontier of Medieval Latin Christianity, CEU Medievalia, 2001,p.72
Adak, Abdurrahman (2022-09-18). Destpêka Edebiyata Kurdî ya Klasîk (in Kurdish). Pak Ajans Yayincilik Turizm Ve Diş Ticaret Limited şirketi. ISBN 978-605-5053-04-8.