@article{IM_1981__63_142789,
     author = {J. Cuntz},
     title = {A {Class} of {C*-algebras} and {Topological} {Markov} {Chains} {II:} {Reducible} {Chains} and the {Ext-functor} for {C*-algebras.}},
     journal = {Inventiones mathematicae},
     pages = {25--40},
     publisher = {mathdoc},
     volume = {63},
     year = {1981},
     zbl = {0461.46047},
     url = {http://geodesic.mathdoc.fr/item/IM_1981__63_142789/}
}