1. Wellenmechanik und halbzahllge Quantisierung;Kramers;Z.Phys.,1926
2. Quantum mechanics and asymptotic series;Birkhoff;Bull. Amer. Math. Soc.,1933
3. Behaviour of some magnitudes of quantum mechanics;Maslov;Dokl. Akad. Nauk SSSR,1954
4. Oscillations of an inhomogeneous plasma in a magnetic field;Rudakov;Zh. eksperim. i teor. fiz.,1959
5. Oscillations of a weakly inhomogeneous plasma;Silin;Zh. eksperim. i teor. fiz.,1963