MR3035421 Samsonov, Boris F. Hermitian Hamiltonian equivalent to a given non-Hermitian one: manifestation of spectral singularity. Philos. Trans. R. Soc. Lond. Ser. A Math. Phys. Eng. Sci. 371 (2013), no. 1989, 20120044, 11 pp. (Reviewer: Camillo Trapani)