Resonance chains in open systems, generalized zeta functions and clustering of the length spectrum
S. Barkhofen, F. Faure, T. Weich, Nonlinearity 27 (2014) 1829–1858.

Dynamics of ionisation and entanglement in the 'atom + quantum electromagnetic field' system
P. Sharapova, O.V. Tikhonova, Quantum Electronics 42 (2012) 199–207.