ATP's Regulatory IA library includes Service Bulletins incorporated by Reference within an AD. You would find a hyperlink inside of the AD applicable to it. They are also listed in My Library and Search in the Associated Service Information folders. Regulatory libraries only include Service Information incorporated by reference in the AD.
If you have a Maintenance Library you can find Service Bulletins by searching via MY LIBRARY tab (Select Cessna & Model Number. All information available for your subscription will be listed.) or by searching via SEARCH tab (Place a check on Service Information, Select Cessna & Model Number, Click on Search for results.). Maintenance Libraries include all current Service Information.
SAIB CE-04-03 is not part of IA library but can be found at http://www.askbob.aero/content/cessna-172-180185-saib-ce-04-03