North Vietnam, 1. Five Year Plan (5. Series), January 25, 1964, Michel Nr. 293-295; Three stamps in the nominals of 6 xu and 12 xu (two stamps) were issued in perforation 11.0.
Here is the mint set.
These stamps were not officially released imperforate however a very small number of imperforate trial proofs have come to market. Here are two of them.
Here is a letter mailed to Klewitz in February of 1964. It contains the entire set plus other North Vietnamese stamps for an overall postage of 52 xu. Required postage for a standard 20 gram letter to West Germany was 50 xu.
Colorful mixed franking on a rare registered letter made up of three of the 12xu Democratic Republic stamps, two of the 40xu Lunar Calendar stamps, three Five Year Plan stamps of both sets and three of the 30xu GANEFO Games stamps for an overall postage of 2.78D. The letter was sent from Hanoi to a newspaper editor in East Germany in May of 1964.
Registration Nr. 100870