M. Q. Tran, V. B. Nguyen, D. D. Pham, P. T. Hoang, N. L. Pham, and T. M. L. Le, “Mechanical properties and thermal stability of poly (L-lactic acid) treated by Co-60 gamma radiation ”, Nucl. Sci. and Tech., vol. 3, no. 2, pp. 21-28, Jun. 2013.