S. Brands, and D. Chaum. Advances in Cryptology, volume 765 of Lecture Notes in Computer Science, Springer Berlin Heidelberg, EUROCRYPT edition, (1994)
N. Borisov, I. Goldberg, and D. Wagner. MobiCom '01: Proceedings of the 7th annual international conference on Mobile computing and networking, page 180--189. New York, NY, USA, ACM, (2001)