http://www.nas.nasa.gov/Main/Features/2001/Fall/wake_detection_pic2.html

"aero". The WIG Page
http://www.se-technology.com/wig/html/main.php?open=aero&code=0

"Ground Effect". Wikipedia
http://en.wikipedia.org/wiki/Ground_effect

"Induced Drag". Professionalpilot
http://www.professionalpilot.ca/aerodynamics/drag/induced.htm

Rozhdestvensky, Kirill V. Aerodynamics of a lifting system
in extreme ground effect. New York: Springer, 2000.

"Section 7 Commentary". Robyn Stewart
http://fly.wabyn.net/FlightTraining/PSTAR/7As.htm

"Winglet". Wikipedia
http://en.wikipedia.org/wiki/Winglet

"Wingtip Vortices". Wikipedia
http://en.wikipedia.org/wiki/Wingtip_vortices