1930, 4th issue, 5k/100r-1r/200r, complete set of five used on reverse of exchange cover from Moscow to Yugoslavia (franked by two values), tied by two violet boxed official handstamps, Belgrade arrival marking, VF and very scarce cover with complete set usage, Standard #PE14-18, Est. $400-$500 (Image)

1930, 4th issue, 1k/250r violet and 25k/300r green, two values with straight edge at one side, used on reverse of exchange cover from Moscow to Switzerland (franked by four stamps), tied by violet boxed official handstamp, Berne arrival marking, VF, Standard #PE15-16, Est. $120-$150 (Image)