@article{DMPS_2008_28_1_a7,
     author = {Kala, Rados{\l}aw},
     title = {On commutativity of projectors},
     journal = {Discussiones Mathematicae. Probability and Statistics},
     pages = {157--165},
     publisher = {mathdoc},
     volume = {28},
     number = {1},
     year = {2008},
     zbl = {1158.15012},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/DMPS_2008_28_1_a7/}
}