New stamps

Yippeee, my new stamps have arrived today. I've been waiting for this shipment for quite sometime. Some of the stamps are very difficult to get and I have to get it from a very specialized stamp dealer in Belgium.
One of the stamp that arrived today is the one on the left side. This one is part of the bigger group, but most of the time, this stamp is not included in the group. The main reason is because it was issued on separate occassion. The whole group was issued in 1949 which consist of a total 17 stamps. Later on another stamp was issued in the same pattern. This one was issued in 1949 as well, but at a later month.
However, the one on the left was not issued until 1952 and also at a much higher value as well. So most people or dealer when they are selling this group tend to "forget" about this particular stamp and just sell them as 17 stamps collection. The actual case in it should have been consisted of a total 19 stamps.

One of my problem with collection is the language limitation. I can only read English and unfortunately, if you want to have a good information, most of the time they are only available in their native origin.
So to get the best information about the German stamps, you should be able to read German, for French stamps then the language is French, etc.
Some of the basic term are understandable without having to learn the language, but the explanation are normally not easy to understand.