@article{10_4064_fm_138_1_1_12,
     author = {Andrea Sorbi},
     title = {Comparing $\ensuremath{\prod}^0_2$ sets of the {Baire} space by means of general recursive operators},
     journal = {Fundamenta Mathematicae},
     pages = {1--12},
     publisher = {mathdoc},
     volume = {138},
     number = {1},
     year = {1991},
     doi = {10.4064/fm-138-1-1-12},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/fm-138-1-1-12/}
}