Includes letters from Speigelberg to: Verlag Johann Ambrosius Barth, Munchen, Germany; Kurt Hobel; Peter Schwankel, Bonn, Germany von Reutern, Deutsche Forschungsgemeinschaft; Peter Schwankel, Bonn, Germany. Includes letters to Speigelberg from: Peter Schwankel, Bonn, Germany; Dr. Scheffels, Deutsche Forschungsgemeinschaft; Josef Habbel, Bonn, Germany von Reutern, Deutsche Forschungsgemeinschaft; Kurt Hobel. Includes letters to Peter Schwankel, Bonn, Germany from: Verlag Johann Ambrosius Barth, Munchen, Germany. Includes letters from Verlag Johann Ambrosius Barth, Munchen, Germany to: Kurt Hobel