SERBIA - Austria. 1871 registered cover, franked with 25o and 50p Prince Milan issue, prepaying the single letter rate plus Registry fee to Austria, and all tied by BELGRAD c.d.s. Front shows boxed "PD" marking and framed RECOMM handstamp, while reverse bears GRATZ arrival c.d.s. A rare franking on a most attractive Registered letter, Ex Burrus and Brodtbeck. Scott 21, 24. (Photo). Est. 500 - 750 CHF.