@article {Heun/2003a,
	title = {{Approximate Protein Folding in the HP Side Chain Model on Extended Cubic Lattices}},
	journal = {Discrete Applied Mathematics},
	volume = {127},
	number = {1},
	year = {2003},
	pages = {163-177},
	keywords = {heun-group},
	doi = {10.1016/S0166-218X(02)00382-7},
	author = {Volker Heun}
}