@article{10_4153_CJM_1974_068_8,
     author = {Fixman, Uri and Zorzitto, Frank A.},
     title = {A {Purity} {Criterion} for {Pairs} of {Linear} {Transformations}},
     journal = {Canadian journal of mathematics},
     pages = {734--745},
     year = {1974},
     volume = {26},
     number = {3},
     doi = {10.4153/CJM-1974-068-8},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-1974-068-8/}
}