Jim Woodcock Susan Stepney David Cooper John A. Clark Jeremy Jacob The certification of the Mondex electronic purse to ITSEC Level E6. 5-19 2008 20 Formal Asp. Comput. 1 http://dx.doi.org/10.1007/s00165-007-0060-5 db/journals/fac/fac20.html#WoodcockSCCJ08