Grigorovich MR-3 explained

The Grigorovich MR-3 (Morskoi Razviedchik - 3) was a prototype maritime patrol flying boat built in the Soviet Union during the late 1920s that was not accepted for production.

References

2. http://www.all-aero.com/index.php/34-planes/20666-grigorovich-rom-1-grigorovich-mr-3

Bibliography

• Book: Gunston, Bill. The Osprey Encyclopedia of Russian Aircraft 1875–1995. Osprey. London. 1995a. 1-85532-405-9. Bill Gunston.
• Kotelnikov. V.. Kulikov. V.. Cony. C.. amp . Les avions français en URSS, 1921–1941 . Avions: Toute l'Aéronautique et son histoire . December 2001 . 105 . 50–56 . French Aircraft in the USSR, 1921–1941 . fr . 1243-8650.