B. Tim Denvir José Nuno Oliveira Nico Plat The Cash-Point (ATM) `Problem'. 211-215 2000 12 Formal Asp. Comput. 4 http://link.springer.de/link/service/journals/00165/bibs/0012004/00120211.htm db/journals/fac/fac12.html#DenvirOP00