The Main Theorem: Cyclic Algebras -- The Paper: Dedication to Hensel -- The Local-Global Principle -- From the Local-Global Principle to the Main Theorem -- The Brauer Group and Class Field Theory -- The Team: Noether, Brauer and Hasse -- The American Connection: Albert -- Epilogue: Käte Hey.The unpublished writings of Helmut Hasse, consisting of letters, manuscripts and other papers, are kept…