Sapkota, K., D. Sah, S. Bhattarai, A. Sharma, J. Shrestha, and D. Shah. “Effectiveness of Pencil Push up Therapy in Patients With Convergence Insufficiency: A Pilot Study”. Health Renaissance, vol. 9, no. 3, Dec. 2011, pp. 157-61, doi:10.3126/hren.v9i3.5583.