@article{MAN_1980__253_163462,
     author = {J. Denef and L. Lipshitz},
     title = {Ultraproducts and {Approximation} in {Local} {Rings.} {II.}},
     journal = {Mathematische Annalen},
     pages = {1--28},
     publisher = {mathdoc},
     volume = {253},
     year = {1980},
     zbl = {0426.13010},
     url = {http://geodesic.mathdoc.fr/item/MAN_1980__253_163462/}
}