Naz, S. et al. 2021. Prevalence and Association of Different Levels of Intellectual Disability with Prenatal, Perinatal, Neonatal and Postnatal Factors: Prevalence and association of levels of ID. Proceedings of the Pakistan Academy of Sciences: B. Life and Environmental Sciences. 58, 3 (Sep. 2021), 75–82. DOI:https://doi.org/10.53560/PPASB(58-3)667.