Here's another interesting set from the collection.
On 29 December 1934, Germany issued this set to postcards to benefit the Winterhilfswerk (Winter Welfare) fund.
Unlike most German postcards of the period, these cards were distributed in a "lotterie" format. The cards were printed in attached pairs. On 90% of the printings, there was no value indicia printed on either card.
On 10% of the printings, however, one of the cards bore a 6 Pf indicia, relieving the user of the need to attach additional postage before mailing. The user would not know if they had "won the lottery" and received a 6 Pf card until opening the sealed package.
Of the 100 pairs, all are available without indicia on either card. On the 10% that were printed with indica, the indicia is always on the same card of the pair (those denoted below with a solid square), commonly known as a "regular" pair. Of the 100 pairs, all are believed to be available in regular pairs, but only 82 have been confirmed. Of those 82 pairs, 20 can also be found with value indicia on the incorrect card within the pair due to printing errors (those denoted below with a hollow square). Of the 18 pairs for which a "regular" variety hasn't been confirmed, 16 pairs are currently only known without indicia, and 2 are known only with the indicia on the incorrect card of the pair.
I currently have about half of the Lotterie cards in my collection. If you'd like to see the rest, you can do so here