http://poincare.matf.bg.ac.rs/~vladaf/Courses/Matf%20UVIT/Predavanja/UVIT01-01-Uvod%20u%20racunarske%20mreze.pdf
http://poincare.matf.bg.ac.rs/~vladaf/Courses/Matf%20UVIT/Predavanja/UVIT01-02-Uvod%20u%20Internet.pdf