@article{MAN_1952__125_160295,
     author = {H. Wang},
     title = {The irreducibility of impredicative principles.},
     journal = {Mathematische Annalen},
     pages = {56--66},
     publisher = {mathdoc},
     volume = {125},
     year = {1952},
     zbl = {0049.16503},
     url = {http://geodesic.mathdoc.fr/item/MAN_1952__125_160295/}
}