Woods 1979, стр. 255 Woods, Carlos C. (1979). „Igor Ivan Sikorsky”. Ур.: National Academy of Engineering. Memorial Tributes. National Academies. NAP:14722.
Woods 1979, стр. 256 Woods, Carlos C. (1979). „Igor Ivan Sikorsky”. Ур.: National Academy of Engineering. Memorial Tributes. National Academies. NAP:14722.
Woods 1979, стр. 256. Woods, Carlos C. (1979). „Igor Ivan Sikorsky”. Ур.: National Academy of Engineering. Memorial Tributes. National Academies. NAP:14722.
Woods 1979, стр. 257. Woods, Carlos C. (1979). „Igor Ivan Sikorsky”. Ур.: National Academy of Engineering. Memorial Tributes. National Academies. NAP:14722.