How to find the Aperture User Manual
The Aperture 3 User Manual is currently missing from the Support pages.
A version has been saved by the Internet Archive here: https://web.archive.org/web/20180504121246/http://documentation.apple.com/en/aperture/usermanual/index.html
Update: It is now back: https://manuals.info.apple.com/MANUALS/1000/MA1560/en_US/Aperture_3_User_Manual.pdf