1. Jahn HA, Teller E (1937) Proc R Soc Lond A 161:220
2. Jahn HA (1938) Proc R Soc Lond A 164:117
3. The Kramers degeneracy theorem states that the energy levels of systems with an odd number of electrons remain at least doubly degenerate in the presence of purely electric fields (i.e. no magnetic fields). Kramers HA (1930) Kon Acad Wet Amsterdam 33:959
4. Bersuker IB (2006) The Jahn-Teller effect. Cambridge University Press, London
5. Ceulemans A, Beyens D, Vanquickenborne LG (1984) J Am Chem Soc 106:5824