1. Alonso, M.A.: Second order differential operators and their eigenfunctions, Talk given at Winter College on Fibre Optics, Fibre Lasers and Sensors, Abdus Salam Center for Theoretical Physics, 5–9 Feb, 2007
2. Aschheim, R., Castro, C., Irwin, K.: The search for a Hamiltonian whose energy spectrum coincides with the Riemann zeta zeroes. Int. J. Geom. Meth. Mod. Phys. 14(6), 1750109–1750137 (2017)
3. Bender, C.M., Boettcher, S.: Real spectra in non-hermitian Hamiltonians having PT symmetry. Phys. Rev. Lett. 80, 5243–5246 (1998)
4. Berry, M.V., Keating, J.P.: The Riemann zeros and eigenvalue asymptotics. SIAM Rev. 41(2), 236–266 (1998)
5. Berry, M.V., Keating, J.P.: H = xp and the Riemann zeros. In: Keating, J.P., Khmelnitskii, D.E, Lerner, I.V. (eds.) Supersymmetry and Trace Formulae: Chaos and Disorders, pp. 355–367. Plenum, New York (1998)