@article{10_4064_fm_81_3_183_192,
     author = {Harvey Friedman},
     title = {Minimality in the ${\ensuremath{\Delta}^1}_2$-degrees},
     journal = {Fundamenta Mathematicae},
     pages = {183--192},
     publisher = {mathdoc},
     volume = {81},
     number = {3},
     year = {1973},
     doi = {10.4064/fm-81-3-183-192},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/fm-81-3-183-192/}
}