http://www.eng.ucy.ac.cy/cpitris/courses/ece623/notes/SignalsAndSystems.pdf

http://users.ece.gatech.edu/~bonnie/book/worked_problems.html

http://florida.theorangegrove.org/og/file/e66b88b8-2801-ee81-1d88-cacd33185dd7/1/Signals.pdf

http://www.google.com/url?sa=t&rct=j&q=signal+and+systems+and+properties&source=web&cd=26&cad=rja&ved=0CE4QFjAFOBQ&url=http%3A%2F%2Faimm02.cse.ttu.edu.tw%2Fclass%2F91-1%2FFourier%2520Analysis%2FSignalSystem.ppt&ei=QoPmUN7NMenK0AWXuoHICA&usg=AFQjCNGXV10YjGXmKX27Skz6JBJZZrT0cA&bvm=bv.1355534169,d.d2k

http://videoprocessing.ucsd.edu/~stanleychan/class/Su11/Book.pdf

http://books.google.com/books?id=XtuS7zCEA10C&pg=PR13&lpg=PR13&dq=signal+and+systems+and+properties&source=bl&ots=JDOO-NUfv3&sig=K-hn056Mf7yyzWUQPyp70kIjeUk&hl=en&sa=X&ei=ksbmUKSkK8js0gXbnoH4Bw&ved=0CFEQ6AEwBTge#v=onepage&q=signal%20and%20systems%20and%20properties&f=false

http://books.google.com/books/about/Signals_And_Systems.html?id=lgx3o2zQm64C

http://www.dspguide.com/ch3/2.htm

http://books.google.com/books/about/Signals_And_Systems.html?id=VgUtRFHXQicC

http://books.google.com/books/about/Signals_And_Systems.html?id=LDadfi_t5xgC

http://books.google.com/books/about/An_Introduction_to_Signal_and_System_Ana.html?id=y5kKqwTHr9sC

http://books.google.com/books/about/Textbook_Of_Signals_And_Systems_Revised.html?id=42mmLVjCEkMC