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 are a few printing errors on which certain color printing runs are missing entirely. Here is mint sample of the 30xu value that misses all of the brown color.
Here is the same stamp but this time missing the entire blue color.
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:
Other perforation errors have become known. Here is mint strip of four of the 12xu value that is imperforate on the left margin and shows an errant perforation strike diagonal across the stamps design.
Mis-perforated pair of the 12xu issue resulting in the country name appearing at the bottom instead of the top.
This is a mint block of four of the 12 xu value that was affected by a paper fold on the top left stamp.
Here is a similar mint block of four from the bottom right of the sheet that shows a double perforation strike in-between the two pairs.
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