Bell Model 409 Advanced Attack Helicopter full-scale mockup
U.S. Dept. of Defense employee
1973-10
<a rel="nofollow" class="external text" href="https://babel.hathitrust.org/cgi/imgsrv/download/pdf?id=uiug.30112106757435;orient=0;size=100;seq=98;attachment=0"><i>Military Review</i></a>, October 1973, Vol. 53, No. 10, Page 96