Adelaja, A. A. “Human Induced Pluripotent Stem Cells Generated Neural Cells Behaving Like Brain and Spinal Cord Cells: An Insight into the Involvement of Retinoic Acid and Sonic Hedgehog Proteins”. International Journal of Health Sciences, vol. 11, no. 2, Apr. 2017, https://pub.qu.edu.sa/index.php/journal/article/view/1844.