Sikorsky R-4 (English Wikipedia)

"Sikorsky R-4B Hoverfly". National Museum of the United States Air Force. Retrieved: 25 July 2016.
"Sikorsky R-4B Hoverfly". National Museum of the US Air Force™. Retrieved 2019-03-24.
"Sikorsky R-4B Hoverfly". National Museum of the United States Air Force. 20 April 2015. Retrieved 14 March 2021.

armyavnmuseum.org

"Rotary Wing Collection". United States Army Aviation Museum. 2 January 2003. Archived from the original on 13 July 2012. Retrieved 15 March 2021.

"Aircraft : R-4 Sikorsky Hover Fly". CAF Operations.org. Archived from the original on 7 May 2021. Retrieved 2 December 2024.

"FAA Registry [N4605V]". Federal Aviation Administration. U.S. Department of Transportation. Retrieved 7 May 2021.

"Hanging around in Ft. Belvoir". Fairfax County Times. 9 February 2019. Retrieved 15 March 2021.

"Britain's Test Pilots, No. 17 Wing Cdr. Reginald Alfred Charles Brie", Flight: 643, 12 December 1946.
"Flight 1946". flightglobal.com. Retrieved 3 April 2018.
"Helicopters for training", Flight, 5 July 1945, retrieved 21 October 2014

"Sikorsky R-4B – Canada Aviation and Space Museum". ingeniumcanada.org. Retrieved 2019-03-24.
"Sikorsky R-4B". Canadian Aviation and Space Museum. Retrieved 14 March 2021.

"HNS Hoverfly". National Naval Aviation Museum. Archived from the original on 3 December 2018. Retrieved 14 March 2021.

"Sikorsky R-4B (S-47) 'Hoverfly'". New England Air Museum. Archived from the original on 6 November 2020. Retrieved 14 March 2021.

Veysey, Arthur (21 Jun 1945). "Lift Yanks out of Luzon by Helicopter". Newspapers.com. Chicago Tribune. Retrieved 9 February 2022.

"Sikorsky R-4B Hoverfly 1". RAF Museum. Retrieved 2023-11-07.
"Sikorsky R-4B Hoverfly 1". Royal Air Force Museum. Retrieved 14 March 2021.
Simpson, Andrew (2007). "Individual History [KL110]" (PDF). Royal Air Force Museum. Archived from the original (PDF) on 23 December 2010. Retrieved 14 March 2021.

"Vought-Sikorsky XR-4C". National Air and Space Museum. Smithsonian Institution. Archived from the original on 28 March 2021. Retrieved 14 March 2021.

"Sikorsky Archives | First Delivery". www.sikorskyarchives.com. Retrieved 2019-03-24.
"S-54 Sesque Tandem Experimental Helicopter". Retrieved 7 December 2021.
"S-47/R-4 Helicopter". sikorskyarchives.com. Retrieved 21 October 2014.

Magazine, Smithsonian; Connor, Roger. "Medevac From Luzon". Smithsonian Magazine. Retrieved 9 February 2022.

"History of Coast Guard Aviation pg. 25" (PDF). uscg.mil. Retrieved 21 October 2014.

Drucker, Graham. "Sikorsky R-4B Hoverfly (HNS)". www.fleetairarmarchive.net. Archived from the original on 31 October 2012. Retrieved 31 March 2013.
Simpson, Andrew (2007). "Individual History [KL110]" (PDF). Royal Air Force Museum. Archived from the original (PDF) on 23 December 2010. Retrieved 14 March 2021.
"Vought-Sikorsky XR-4C". National Air and Space Museum. Smithsonian Institution. Archived from the original on 28 March 2021. Retrieved 14 March 2021.
"Sikorsky R-4B (S-47) 'Hoverfly'". New England Air Museum. Archived from the original on 6 November 2020. Retrieved 14 March 2021.
"Our Collection – Restoration Hangar". Yanks Air Museum. Archived from the original on 18 July 2011. Retrieved 14 March 2021.
"Rotary Wing Collection". United States Army Aviation Museum. 2 January 2003. Archived from the original on 13 July 2012. Retrieved 15 March 2021.
"HNS Hoverfly". National Naval Aviation Museum. Archived from the original on 3 December 2018. Retrieved 14 March 2021.
"Aircraft : R-4 Sikorsky Hover Fly". CAF Operations.org. Archived from the original on 7 May 2021. Retrieved 2 December 2024.

"Our Collection – Restoration Hangar". Yanks Air Museum. Archived from the original on 18 July 2011. Retrieved 14 March 2021.

"Sikorsky R‑4B Hoverfly". Yanks Air Museum. 5 February 2017. Retrieved 14 March 2021.