00556cam a22001694a 4500020001500000050001900015100001900034245008900053250001200142260006600154300003700220500002000257650002300277650003600300650003100336700001900367  a013093047400aTK 5105.5bDUC1 aDuck, Michael.10aData communications and computer networks :bfor computer scientists and engineers /  a2nd ed.  aHarlow, England ;aNew York :bPearson/Prentice Hall,cc2003.  axx, 415 pages :bIllustrations ;  aIncludes index. 0aComputer networks. 0aOSI (computer network standard) 0aData transmission systems.1 aRead, Richard.