Some links to web sites with rules and regulations that I’ve found useful.
EASA regulations – This is EASA’s regulation portal. If you haven’t already, read my quick guide to EASA regulations.
ICAO Annexes and Documents – This is perhaps esoterica, but if you really want to understand procedures and regulations you need to read annexes to the International Convention on Civil Aviation and various documents on Standards and Recommended Practises published by the ICAO. This Swiss government web site gives free access to the most important ones. Several of these documents must otherwise be bought from the ICAO at horrendous prices – they are very difficult to find on the web.