http://ncatlab.org/nlab/show/%C4%8Cech+model+structure+on+simplicial+presheaves
http://nlab.mathforge.org/nlab/show/Universal+Homotopy+Theories
http://mathoverflow.net/questions/30140/how-many-model-categories-have-the-same-weak-equivalences
nLab page on Simplicial presheaves II