Unified Vietnam, Stamp Exhibition Philaserdica, May 27th, 1979, Michel Nr. 1038-1039; Two stamps with nominals of 12 xu and 30 xu were issued in perforation 11.75.
Here are mint blocks of four of the set:
There also appear to be two distinct perforation varieties. One shows “normal” perforation holes while the other shows unusually large perforation holes. In both cases though the perforation amounts to 11.75. This may indicate that the perforation combs used for the issue were re-tooled during the process. Here is a block of four of the 30 xu value that shows the large perforation holes:
Very rare registered express mail letter sent to Klewitz in May of 1980. It carries the Stamp Exhibition set plus the 12 xu Einstein stamp without the black printing run. Error stamps on postally used cover are very rare. The overall postage amounted to 4.94 Dong. Hannover-Frankfurt train transit and Fulda arrival cancel on the reverse. Green Fulda custom cancel on front.
Spectacular mass franking of the Five Year Plan series on a large registered express mail envelope mailed to Klewitz in October of 1980. The letter carries a number of the perforation errors of this set. There are also five of the 12 xu Stamp Exhibition stamps. The overall postage amounted to 6.14 Dong. Hand-made express mail label using a typewriter. Fulda arrival cancel on the reverse.
Rare registered express mail letter sent from Ho Chi Minh City to Klewitz in April of 1981. It features a block of four of the 20 xu KPdSU stamp plus two pairs of the the two perforation varieties of the 12 xu Five Year Plan stamp plus one of the 12 xu Stamp Exhibition stamps for an overall postage of 13.90 Dong. Fulda arrival cancel on the reverse. Green Fulda custom cachet on front.
Registration Nr. 102820