The archive of the Brandenburg-Berlinish dictionary contains all of the material that was assembled and evaluated for the dictionary’s production. This includes, for example:
- An extensive library holding the dialectological literature, text collections, dictionaries, regional literature, and dialectological atlases and historical literature that are relevant to the language area.
- The most important source for the dictionary are 22,454 questionnaires . From 1950 to 1959, 22 different questionnaires were sent in multiple stages to over 2000 schools in the region under study. These questionnaires were filled out by informants who had lived the longest in a location and were the oldest; teachers provided assistance. The response rate was over 50%, yet fell from north to south.
- In addition to the questionnaires, audio recordings from about 100 locations constitute another important source. Most of the on-site recordings were done in the 1960s and 1970s and were systematically recovered by colleagues working on the dictionary. There were texts to be read aloud as well as opportunities for free narration.
There are about 1.5 million handwritten notes about information about the individual lemmas drawn from the questionnaires and from other sources. Because historical sources were also evaluated, the findings extend back to the early nineteenth century.