TANNU TUVA. 1932 registered cover to Siberian railway station SHIRA, franked on reverse with provisional surcharged revenue stamp 15k/6k orange type 3 (5,2mm in high) in combination with Wheel of Truth and 18k triangular Sheep Herding 1927 issue stamp. All are tied by Kizil c.d.s. Arrival c.d.s. on reverse. Rare commercial usage of provisional surcharged stamp. (Photo). Est. 400 - 500 CHF.