This map was created with R software package tmap, supported by packages rgdal, proj4, rgeos, tmaptools and OpenStreetmap (and other auxiliary packages loaded by these). The background map comes from OpenStreetMap.
Geometries for Berlin electoral constituencies have been obtained from Berlin authorities (creative commons license with naming the source).
Structural data on electoral constituencies have been obtained from <www.wahlen-berlin.de> at this direct link. The referendum results have also been obtained there at this direct link.
Map data for Tegel noise lines (which artificially end at the Berlin border) have been obtained from Berliner Zeitung (as a shape file).