Gupta, R., B. Sharma, R. Anand, S. Bawaria, and R. Dewada. “Association of Asthenopia and Convergence Insufficiency in Children With Refractive Error- A Hospital Based Study”. International Journal of Medical Research and Review, Vol. 1, no. 5, Dec. 2013, pp. 222-7, doi:10.17511/ijmrr.2013.i05.02.