@article{10_4153_CJM_1976_120_3,
     author = {Stahl, Stanley H.},
     title = {A {Hierarchy} on the {Class} of {Primitive} {Recursive} {Ordinal} {Functions}},
     journal = {Canadian journal of mathematics},
     pages = {1205--1209},
     year = {1976},
     volume = {28},
     number = {6},
     doi = {10.4153/CJM-1976-120-3},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-1976-120-3/}
}