NASA CR  / 2421-30 <br/>
Padakannaya, Raghuveera <br/>
       NASA contractor report NASA CR-2421 : the vortex lattice method for the rotor-vortex interaction problem 
 / Raghuveera Padakannaya 
 .- Washington: National aeronautics and space administration,  1974 
 .- various pagings.. 
<br/>NASa TR102435-TR7942