Ullah, F.; Mahsood, N.; Mohyuddin, W.; Afridi, S.; Rehman, Z. ur. Prevalence of Refractive Error and Strabismus in Primary School Children of Tehsil Lakki Marwat, Khyber Pakhtunkhwa Pakistan. J Gandhara Med Dent Sci 2020, 7, 11-21.