@article{10_4064_sm_45_3_239_240,
     author = {W. \.Zelazko},
     title = {On a problem concerning joint approximate point spectra},
     journal = {Studia Mathematica},
     pages = {239--240},
     publisher = {mathdoc},
     volume = {45},
     number = {3},
     year = {1973},
     doi = {10.4064/sm-45-3-239-240},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/sm-45-3-239-240/}
}