PeopleBooks Guides: The Search for Install & Upgrade Guides
Almost on a daily bases questions arise as to what upgrade paths are supported and often the answer to that question changes. My Oracle Support (MOS) has the answer, however, that answer can be extremely difficult to find.
A little hidden gem of the PeopleBooks Online Reference homepage is they have a link to the current PeopleBooks Guides for Install and Upgrade pages.
Simply expand the category you want and it will link you to the MOS support page associated the guide you are looking for.