Helmut Seidl Kumar Neeraj Verma Flat and One-Variable Clauses for Single Blind Copying Protocols: The XOR Case. 118-132 2009 RTA http://dx.doi.org/10.1007/978-3-642-02348-4_9 conf/rta/2009 db/conf/rta/rta2009.html#SeidlV09