1866, The fantastic and UNIQUE 3 k. IMPERFORATED PAIR, on horiz. laid paper, used in Wloclawek, POLAND with 31. May 1876 c.d.s. The rarest imperforated variety of Russia according to P. Ferrary. A very important item for great collections of Russia or Poland. Ex Ferrary (sold to Sir John Wilson). (Sc. 20b; Mikulski cert.).