Kalappan, M., N. R. T. Abubacker, M. Shetty, K. Rajendran, W. K. M. Rathinam, and R. Karuthodiyil. “Study of Extra-Articular Manifestations and Disease Severity in Patients With Rheumatoid Arthritis”. International Journal of Advances in Medicine, vol. 3, no. 1, Jan. 2017, pp. 53-56, doi:10.18203/2349-3933.ijam20160188.