@article{Maciejewski:2015,
  author  = "A. Maciejewski and M. Przybylska and T. Stachowiak",
  title   = "Comment on "Solvability of the two-photon Rabi Hamiltonian"",
  journal = "Physical Review A",
  volume  = "Vol. 91",
  pages   = "1--2",
  year    = "2015",
}