@article{JRAM_1980__313_152195,
     author = {Stefan Heinrich},
     title = {Ultraproducts in {Banach} space theory.},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {72--104},
     publisher = {mathdoc},
     volume = {313},
     year = {1980},
     zbl = {0412.46017},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1980__313_152195/}
}