PROVISIONAL BISECT: 1928, Exchange Fee Stamp 10 k. on 250 r. violet, diagonal bisect, tied by official exchange office cachet to reverse of registered envelope to Vienna, correct 28 kopek franking on obverse tied by cds. "MOSCOW -6 X 28", alongside larger departure cds. "MOSCOW -7 10 28", reverse arrival receiver cds. "WIEN 66 -9. X. 28". Very fine, a very rare usage probably due to the shortage of 5 kopek exchange stamp in October 1928 in Moscow, certificate Leupold (2021)
