@article{10_4064_fm_121_3_239_250,
     author = {Kenneth Schilling},
     title = {On absolutely $\ensuremath{\Delta}^1_2$ operations},
     journal = {Fundamenta Mathematicae},
     pages = {239--250},
     publisher = {mathdoc},
     volume = {121},
     number = {3},
     year = {1984},
     doi = {10.4064/fm-121-3-239-250},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/fm-121-3-239-250/}
}