German Reich - Kraft Durch Freude Piece

Here is another thing I picked up recently.
Perhaps anyone here can tell if it is anything special? The stamps are from booklets and in that way already more interesting than the "ordinary" ones.

I've never seen those before. But seeing that they are "Gedenkblätter", they are the German Reich equivalent of the "cardboard philately" we're having today with FDCs and all that.

Just one interesting thing to know is maybe that back then the German territories were organized in so called "Reichsgaue". You can read that at the bottom of the card, "Gau Hamburg".
A "Gau" beeing a term for an area of land. Interestingly, TODAY "Gau" in German is used as an abbreviation for "Größter anzunehmender Unfall"... "Worst accident thinkable"