Wikimedia
Wikipedia: William George Barker
A biography and military history of one of WWI's most famous flying Aces.
First World War
First World war.com: Aviation Photographs
An extensive amount of aviation photographs from WWI. There is also a link to introductory notes on aviation and aviators in the war.
Other
Ace Pilots: Billy Bishop
A biography on one of the most successful and notorious of WWI flying Aces. Quotes are included here.