@article{10_4064_ba55_4_3,
     author = {Andrzej Pr\'oszy/nski},
     title = {Relations between {Elements} $r^{2}-r$},
     journal = {Bulletin of the Polish Academy of Sciences. Mathematics},
     pages = {317--323},
     publisher = {mathdoc},
     volume = {55},
     number = {4},
     year = {2007},
     doi = {10.4064/ba55-4-3},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/ba55-4-3/}
}