Today's document, R-142, is about the 10 April '38 plebiscite to approve the annexation of Austria. One of the final 2 elections held by the Third Reich (the final one was later that year, concerning the Sudetenland). German slogan was "One people, one Reich, one Führer." 
2/ This is the ballot for the plebiscite. Note the strictly neutral design. Everyone was expected to give full support to Hitler and the annexation.
3/ After the ballots were counted, it seems there were a few dissenters. This SD letter from Koblenz shows how these people were identified, using numbered ballots (actual paper ballots - no machines). "Marking was done on back of ballot-papers with skimmed milk." (sic)
4/ In this close up you can read the procedure: ballots handed out in numerical order to a predetermined list of voters. (sadly, there were 2 people of same name in village, so it wasn't perfect.)
5/ Given the propaganda prior to the election, the fact that 0.91% of Germans voted "NO" is heartening (many fewer did so in Austria). The docs in this file don't reveal what happened to these brave people.
6/ 45 million (out of 68 million) Germans voted. Perhaps they sensed this would be nearly their last chance to vote for many years (the final election was Dec '38, for Reichstag seats "representing" the Sudetenland; the Reichstag convened only 7 more times prior to 1945.) ///
7/ Last note: 2000 Germans living in the UK were taken 50 miles out to sea on the Wilhelm Gustloff in order to vote in this critical election. 99.4% voted "JA!" (Life Magazine, May 2 1938).
