Walker 2014, p. 255. Walker, Paul Ernest (2014). "Sijistānī, Abū Yaʿqūb al-". In Kalin, Ibrahim (ed.). The Oxford Encyclopedia of Philosophy, Science, and Technology in Islam. Oxford: Oxford University Press. pp. 255–257. ISBN978-0-19-981257-8.
Walker 2014, p. 256. Walker, Paul Ernest (2014). "Sijistānī, Abū Yaʿqūb al-". In Kalin, Ibrahim (ed.). The Oxford Encyclopedia of Philosophy, Science, and Technology in Islam. Oxford: Oxford University Press. pp. 255–257. ISBN978-0-19-981257-8.