http://en.wikipedia.org/wiki/Feather (http://en.wikipedia.org/wiki/Feather)
http://en.wikipedia.org/wiki/Flight_feather (http://en.wikipedia.org/wiki/Flight_feather)
http://en.wikipedia.org/wiki/Down_feather (http://en.wikipedia.org/wiki/Down_feather)
http://globalflyfisher.com/staff/luallen/feather0.htm (http://globalflyfisher.com/staff/luallen/feather0.htm)