A Generalized Vertex Operator Algebra for Heisenberg Intertwiners
  We consider the extension of the Heisenberg vertex operator algebra by all its irreducible modules. We give an elementary construction for the intertwining vertex operators and show that they satisfy a complex parametrized generalized vertex operator algebra. We illustrate some of our results with the example of integral lattice vertex operator superalgebras. 
Michael P. Tuite and Alexander Zuevsky
math.QA hep-th