Global homotopy formulas on q-concave CR manifolds for large degrees
  Using functional analysis and a Friedrichs approximation lemma for first order differential operators, we derive a global homotopy formula in large degrees for the tangential Cauchy-Riemann operator from local homotopy formulas without loss of regularity. 
Till Br\"onnle, Christine Laurent-Thi\'ebaut (IF), J\"urgen Leiterer