Zhifang Zhang Yeow Meng Chee San Ling Mulan Liu Huaxiong Wang Threshold changeable secret sharing schemes revisited. 106-115 2012 418 Theor. Comput. Sci. http://dx.doi.org/10.1016/j.tcs.2011.09.027 db/journals/tcs/tcs418.html#ZhangCLLW12