Helikopter ini banyak terlibat di misi-misi SAR (search and rescue) di kawasan Asia semasa Perang Dunia II. Sikorsky R-4 terlibat dalam misi CSAR (combat SAR) pertama yang dilakukan menggunakan helikopter pada April 1944 di teater China-India-Burma.
Cocker, Maurice. Aircraft-Carrying Ships of the Royal Navy. Stroud, Gloucestershire, UK: The History Press, 2008 ISBN 978-0-7524-4633-2.
McGowen, Stanley S. Helicopters: An Illustrated History of Their Impact (Weapons and Warfare Series). Santa Barbara, CA: ABC-CLIO, 2005. ISBN 978-1-85109-468-4.
Myall, Eric and Ray Sturtivant (ed.). The Hoverfly File. Tunbridge Wells, Kent, UK: Air-Britain (Historians) Ltd., 1998. ISBN 0-85130-262-9.
United States Air Force Museum Guidebook. Wright-Patterson AFB, Ohio: Air Force Museum Foundation, 1975.
Williams, Dr. James W. A History Of Army Aviation: From Its Beginnings To The War On Terror. Bloomington, IN: Iuniverse, 2005. ISBN 978-0-595-67396-4.
Pranala luar
Wikimedia Commons memiliki media mengenai Sikorsky R-4.