أول طائرة هليكوبتر

1. Igor Sikorsky | Lemelson [Internet]. Lemelson.mit.edu. [cited 4 October 2022]. Available from: هنا

2. The National Medal of Science 50th Anniversary | Igor I. Sikorsky (1889-1972) [Internet]. National Science Foundation. [cited 4 October 2022]. Available from: هنا

3. Igor Sikorsky, inventor of the practical helicopter | National Air and Space Museum [Internet]. Airandspace.si.edu. [cited 4 October 2022]. Available from: هنا

4. Giges N. Igor Sikorsky: Aviation Pioneer [Internet]. Asme.org. 2013 [cited 4 October 2022]. Available from: هنا