1. W Dai,a scheme for a group of untraceable digital pseudonyms to pay each other with money and to enforce contracts amongst themselves without outside help,“B-money”,http://www.weidai.com/bmoney.txt,1998
2. W.Feller,"An introduction to probability theory and its applications," 1957
3. H.Massias,X.S.Avila,and J.-J.Quisquater,"Design of a secure timestamping service with minimal trust requirements,"In 20th Symposium on Information Theory in the Benelux,May 1999.
4. S.Haber,W.S.Stornetta,"How to time-stamp a digital document," In Journal of Cryptology,vol 3,No.2,pages 99-111,1991.
5. D.Bayer,S.Haber,W.S.Stornetta,"Improving the efficiency and reliability of digital time-stamping,"In Sequences II: Methods in Communication,Security and Computer Science,pages 329-334,1993.
6. 5.S.Haber,W.S.Stornetta,"Secure names for bit-strings," In Proceedings of the 4th ACM Conference on Computer and Communications Security,pages 28-35,April 1997.on Computer and Communications Security,pages 28-35,April 1997. 7.A.Back,"Hashcash-a denial of service counter-measure,"http://www.hashcash.org/papers/hashcash.pdf,2002.