@article{10_4064_fm_75_3_223_234,
     author = {Andrzej Mostowski},
     title = {Models of second order arithmetic with definable {Skolem} functions},
     journal = {Fundamenta Mathematicae},
     pages = {223--234},
     publisher = {mathdoc},
     volume = {75},
     number = {3},
     year = {1972},
     doi = {10.4064/fm-75-3-223-234},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/fm-75-3-223-234/}
}