@inbook {55204921,
	title = {Quantum Ergodicity and Intensity Fluctuations},
	booktitle = {Chaotic Behavior in Quantum Systems},
	year = {1985},
	pages = {255-292},
	publisher = {Springer US},
	organization = {Springer US},
	address = {Boston, MA},
	abstract = {Flow in phase space is intimately related to the concept of ergodicity. An ergodic system will sample all regions of phase space democratically in the time average, subject only to known a priori constants of the motion. For convenience, we shall refer to the accessible phase space as the {\textquotedblleft}energy shell.{\textquotedblright} This shell may have some thickness if a distribution of energies are initially populated An energy envelope is defined by the initial distribution of energy and the envelope plays a role both in classical and quantum phase Space flow, as discussed before and as will become evident in the theory and examples to follow.},
	url = {http://dx.doi.org/10.1007/978-1-4613-2443-0_18},
	author = {E. J. Heller and R. L. Sundberg}
}
