“…In the semiclassical spectral analysis of non-selfadjoint operators in dimension 2, the work [25] elucidated the rôle played by certain flow invariant Lagrangian tori in the complexified phase space, and showed how the latter could be used to obtain complete asymptotic expansions for all eigenvalues in suitable domains in the complex spectral plane, in the spirit of the classical Bohr-Sommerfeld quantization condition, well known in dimension one [9], [4], [8]. In the context of small non-selfadjoint perturbations of selfadjoint operators, the work [25] has been pursued in a series of papers [15], [16], [17], [31], under the additional assumption that the classical flow of the unperturbed part should be periodic in a fixed energy shell.…”