@article{10_4064_fm_42_1_38_54,
     author = {J. {\L}o\'s},
     title = {On the extending of models {(I)}},
     journal = {Fundamenta Mathematicae},
     pages = {38--54},
     publisher = {mathdoc},
     volume = {42},
     number = {1},
     year = {1955},
     doi = {10.4064/fm-42-1-38-54},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/fm-42-1-38-54/}
}