SDL documentation is available online from the sidebar on the left,
or downloadable as archives from the links on this page.
HTML documentation:
sdldoc-html.tar.gz
sdldoc-html.zip
UNIX "man" pages:
sdldoc-man3.tar.gz
Windows Help format: (thanks to Lea Anthony)
SDLRef.chm
Printable Postscript:
sdldoc-ps.tar.gz
sdldoc-ps.zip