Bibliografia

What Is DSL - http://www.everythingdsl.com/whatis/
Types of DSL - http://www.everythingdsl.com/types/index.shtml
DSL Glossary - http://www.adsl.com/PressRoom/DSL_Glossary523.html
ADSL Tutorial - http://www.adsl.com/aboutdsl/adsl_tutorial.html
How ADSL Works - http://www.zdnet.com/pccomp/features/excl0198/dsl/adsl2a.html