M. Carmen Ruiz Diego Cazorla Fernando Cuartero Juan José Pardo A Formal Specification and Performance Evaluation of the Purchase Phase in the SET Protocol. 239-244 2005 conf/synasc/2005 SYNASC http://doi.ieeecomputersociety.org/10.1109/SYNASC.2005.4 db/conf/synasc/synasc2005.html#RuizCCP05