@article{MZ_1990__204_3_183765,
     author = {Ronald S. Irving},
     title = {Singular {Blocks} of the {Category} {O.}},
     journal = {Mathematische Zeitschrift},
     pages = {209--224},
     publisher = {mathdoc},
     volume = {204},
     number = {3},
     year = {1990},
     zbl = {0715.17010},
     url = {http://geodesic.mathdoc.fr/item/MZ_1990__204_3_183765/}
}