@article{CM_1987__61_3_353_0,
     author = {Hilton, Peter and Roitberg, Joseph},
     title = {Relative epimorphisms and monomorphisms in homotopy theory},
     journal = {Compositio Mathematica},
     pages = {353--367},
     publisher = {Martinus Nijhoff Publishers},
     volume = {61},
     number = {3},
     year = {1987},
     mrnumber = {883488},
     zbl = {0624.55005},
     language = {en},
     url = {http://archive.numdam.org/item/CM_1987__61_3_353_0/}
}