J. Sjostrand, ADIABATIC PROJECTIONS FROM THE PSEUDODIFF ERENTIAL POINT-OF-VIEW, Comptes rendus de l'Academie des sciences. Serie 1, Mathematique, 317(2), 1993, pp. 217-220
In this Note we show how the use of format pseudodifferential operator
s permits to recover the construction and a fundamental property of a
certain family of projections, which plays an important role in linear
adiabatic theory.