The Grigorovich MU-2 was a trainer flying boat built in the Soviet Union in the mid-1920s. It was designed by the Grigorovich Design Bureau after the failure of the Grigorovich MUR-1, featuring an all-metal hull. However, it was never put into production due to poor performance and sluggish take-off behavior.[1]
Shavrov, V. B. (1985). История конструкций самолетов в СССР (in Russian). Moscow: Машиностроение. pp. Vol 1 pp.401-402.
Kulikov, Victor (December 1996). "Le fascinante histoire des hydravions de Dimitry Grigorovitch" [The Fascinating History of the Seaplanes of Dimitry Grigorovitch]. Avions: Toute l'aéronautique et son histoire (in French) (45): 20–33. ISSN1243-8650.