Nord Vietnam, For War Invalids, issued in 1966 (according to the official Vietnamese Postage Stamp Catalogue), Michel Nr.29 II; A single stamp was issued in sheets of 100 and 120 stamps and in perforation 11.0. The design was identical to the design of Michel Nr. 29 I. The stamps were produced by the Tien Bo Printing House. In the similar/same design series this stamp is the second rarest (as compared to the 1963 and 1965 stamps). Michel indicates that this stamp was issued in 1978 but this cannot be the case as the editor possesses a postally used letter that was sent in 1975 (see below).
Here is the mint stamp with left selvage.
Mint block of four with top selvage.
This stamp was not officially released imperforate however a very small number of imperforate trial proofs have come to market. Very rare.
There must have been at least two printings of this stamp because a stamp has appeared that has a green -olive background, is printed flatter paper and shows much better perforations than the standard stamps. Below is this color/print variety (on the left) next two a pair of the normal stamps.
Very rare postally used local letter sent from a military hospital in Hanoi to Saigon in September of 1975. The stamp used is of the olive-green background variety.
Registration Nr. 101261