@article{10_4064_fm_138_2_103_111,
     author = {Krzysztof Mazur},
     title = {$F_\ensuremath{\sigma}$-ideals and $\ensuremath{\omega}_1 \ensuremath{\omega}^*_1$-gaps in the {Boolean} algebras {P(\ensuremath{\omega})/I.}},
     journal = {Fundamenta Mathematicae},
     pages = {103--111},
     publisher = {mathdoc},
     volume = {138},
     number = {2},
     year = {1991},
     doi = {10.4064/fm-138-2-103-111},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/fm-138-2-103-111/}
}