@article{10_4064_fm_98_1_1_19,
     author = {Karel Hrbacek},
     title = {Axiomatic foundations for {Nonstandard} {Analysis}},
     journal = {Fundamenta Mathematicae},
     pages = {1--19},
     publisher = {mathdoc},
     volume = {98},
     number = {1},
     year = {1978},
     doi = {10.4064/fm-98-1-1-19},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/fm-98-1-1-19/}
}