1. R.H. Landau, Quantum Mechanics II, Wiley, New York, 1989.
2. Real Spectra in Non-Hermitian Hamiltonians HavingPTSymmetry
3. M.V. Berry, D.H.J. O'Dell, J. Phys. A 31 (1998) 2093; F. Cannata, G. Junker, J. Trost, Phys. Lett. A 246 (1998) 219, and references therein.
4. E. Delabaere, F. Pham, Phys. Lett. A250 (1999) 25; E. Delabaere, F. Pham, Phys. Lett. A250 (1998) 29; C.M. Bender, G.V. Dunne, quant-ph/9812039; C.M. Bender, K.A. Milton, hep-th/9802184; A.A. Andrianov, F. Cannata, J. Dedonder, M.V. Ioffe, quant-ph/9806019.
5. S. Gasiorowicz, Quantum Physics, Wiley, Singapore, 1974.