Tanenbaum :
PDFs http://authors.phptr.com/tanenbaumcn4/chapters/coverPageChapters.html
PPTs http://authors.phptr.com/tanenbaumcn4/webResources/coverPageWebResources.html
http://authors.phptr.com/tanenbaumcn4/
Forouzan
http://www.mhhe.com/engcs/compsci/forouzan/dcn/student_index.mhtml
Keiser
http://www.mhhe.com/engcs/electrical/keiser2/
Forouzan
http://highered.mcgraw-hill.com/sites/0072336056/student_view0/
TCP/IP: http://www.mhhe.com/engcs/compsci/forouzan/tcpipppt.mhtml
