@article {HodgdonS93,
	title = {Derivation of a general 3-dimensional crack-propagation law - a generalization of the principle of local symmetry},
	journal = {Physical Review B},
	volume = {47},
	year = {1993},
	pages = {4831-4840},
	author = {Hodgdon, J. A. and Sethna, J. P.}
}
