@article{MM2_1992__77_2-3_155779,
     author = {J\"urgen Herzog and Winfried Bruns},
     title = {On the computation of a-invariants.},
     journal = {Manuscripta mathematica},
     pages = {201--214},
     publisher = {mathdoc},
     volume = {77},
     number = {2-3},
     year = {1992},
     zbl = {0783.13018},
     url = {http://geodesic.mathdoc.fr/item/MM2_1992__77_2-3_155779/}
}