@article{AMLG_1970__13_137841,
     author = {S.S. Wainer},
     title = {A classification of the ordinal recursive functions.},
     journal = {Archiv f\"ur mathematische Logik und Grundlagenforschung},
     pages = {136--153},
     publisher = {mathdoc},
     volume = {13},
     year = {1970},
     zbl = {0228.02027},
     url = {http://geodesic.mathdoc.fr/item/AMLG_1970__13_137841/}
}