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2. Operator Methods;Maslov,1973
3. Stability of inhomogeneous states and functional integrals;Iordanskii;Zh Eksp Teor Fiz,1988
4. Quantized Riemann surfaces and quasiclassical spectral series for a non-self-conjugate Schrödinger operator with periodic coefficients;Gal’tsev;Teor Mat Fiz,2006
5. The Spectrum and pseudospectrum of a non-self-conjugate Schrödinger operator with periodic coefficients;Gal’tsev;Mat Zametki,2006