00337nam a2200121 a 450000500170000002000150001708200200003210000220005224500700007425000120014426000390015630000200019520251203091636.0  a047183727X  a658.05,bD, fit  aFitzGerald, Jerry  aBusiness data communications: basic concepts, security and design  a2nd ed.  aNew YorkbJohn Willey & Sonsc1988  axix, 655p, 24cm