@article{RSMUP_1967__39__248_0,
     author = {Barback, Joseph},
     title = {Regressive upper bounds},
     journal = {Rendiconti del Seminario Matematico della Universit\`a di Padova},
     pages = {248--272},
     publisher = {Seminario Matematico of the University of Padua},
     volume = {39},
     year = {1967},
     mrnumber = {224464},
     zbl = {0159.01002},
     language = {en},
     url = {http://www.numdam.org/item/RSMUP_1967__39__248_0/}
}