T. V. Thang, N. V. Khoi, P. T. Thu Ha, T. D. Cong, H. T. Phuong, and N. V. Manh, “Systhesis and characterization of poly (N-vinyl pyrrolidon – co-vinyl acetate)”, Vietnam J. Sci. Technol., vol. 52, no. 3, pp. 349–355, Jul. 2014.