@article{10_4064_sm211_3_5,
     author = {Roman Drnov\v{s}ek},
     title = {Once more on positive commutators},
     journal = {Studia Mathematica},
     pages = {241--245},
     publisher = {mathdoc},
     volume = {211},
     number = {3},
     year = {2012},
     doi = {10.4064/sm211-3-5},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/sm211-3-5/}
}