Bogdan D. Czejdo Tadeusz Morzy Knowledge, Knowledge Security, and Meta-knowledge. 245-252 2008 WSKS (2) http://dx.doi.org/10.1007/978-3-540-87783-7_31 conf/wsks/2008-2 db/conf/wsks/wsks2008-2.html#CzejdoM08