1. Rizzi,S.A.,Huff,D.L.,Boyd,D.D.,Bent,P.,Henderson,B.S.,Pascioni,K.A.,Sargent,D.C.,Josephson,D.L.,Marsan,M., He,H.B.,etal."Urbanairmobilitynoise: Currentpractice,gaps,andrecommendations,"Tech.rep.,NASA,2020.
2. Shetty, O.,andSelig,M."Small-scalepropellers operatinginthevortexringstate,"49thAIAAAerospaceSciencesMeeting includingtheNewHorizonsForumandAerospaceExposition,2011,p.1254.
3. Vortex ring state as a cause of a single-rotor helicopter unanticipated yaw