Analysis of invariant PDO's on the Heisenberg group
  In these lecture notes, the representation theory of the Heisenberg group as well as Howe's construction of the metaplectic group by means of twisted convolution operators with generalized, complex Gaussians are reviewed, and it is shown how these tools can be successfully applied to the study of local solvability for second order left-invariant differential operators on the Heisenberg group. 
Detlef M\"uller
math.AP