Aerodynamics
From 229ahb
Rotary-Wing Aerodynamics & Rotary Flight
Animations
Induced Flow
http://avimator.net/inducedflow.htm
Vortex Ring State
http://avimator.net/vortexringstate.htm
Wing Tip Vortices
http://avimator.net/WingTipVortices.htm
NOTES
ONLY links to a few solid articles here. Topic is to vast to just add random subtopics on this subject.
Maybe add US Army Flight And FAA guide here as well. Both also offer good fundamental rotary aerodynamics,.