@article{MZ_1980__174_173004,
     author = {Martin Huber and Paul C. Eklof},
     title = {On the {Rank} of {Ext.}},
     journal = {Mathematische Zeitschrift},
     pages = {159--186},
     publisher = {mathdoc},
     volume = {174},
     year = {1980},
     zbl = {0424.20051},
     url = {http://geodesic.mathdoc.fr/item/MZ_1980__174_173004/}
}