1Baker J W.The“classroom nip”:Using web course management tools to become the guide by the side[R].Jacksonville,Florida:Paper Presented at the 11th Intenational Conference on College Teaching and Learing,2000.
2Shamir A.How to share a secret[J].Communications of the ACM,1979,22(11):612-613.
3Blakeley G R.Safeguarding cryptographic keys:Proceeding of the national computer conference[M].New York:AFIPS Press,1979:313-317.