Unpublished documents
Documents of various types concerning the breaking of the Geheimschreiber in FRA's secret archives.
Published works
Carlgren, Wilhelm M, Svensk underrättelsetjänst 1939-1945, (Stockholm 1985).
Kahn, David, The Codebreakers, (New York 1967)
Annotation
The publication of information from FRA's archives has taken place with due permission.
Notes
1. Where no other source is given, the account is based on information from Försvarets Radioanstalt's (FRA) documents.
2. Carlgren, p. 32.
3. Resumé of experts in FRA's documents, compare with Kahn, p. 478.
4. After Carl Gösta Borelius' unpublished documents in FRA's archive.
5. Carlgren, p. 68.
6. Carlgren, p. 80, compare with Borelius' documents.
7. Carlgren, p. 179.