00305nam a2200109Ia 4500003000400000008004100004040000800045100002200053245006500075260004200140300001300182LDD181029s9999    xx            000 0 und d  cLDD  aDavies, Donald W. 0aTutorialbThe security of data in networkscDonald W. Davies  aNew YorkbIEEE computer societyc1981  avi, 241p