Gutenberg (Project): https://www.gutenberg.org/
Gyricon Media: http://www.gyriconmedia.com/
Handicapzéro: http://www.handicapzero.org/
HarperCollins (PerfectBound): http://www.harpercollins.com/hc/perfectbound/
Harry Potter (J.K. Rowling): http://www.jkrowling.com/
Harry Potter (Scholastic): http://www.scholastic.com/harrypotter/home.asp
HighWire Press: http://www.highwire.org/
HLT (Human Language Technologies) Central: http://www.hltcentral.org/
HTML (W3C): http://www.w3.org/MarkUp/
HTTP (W3C): http://www.w3.org/Protocols/