@article{IVM_1980_5_a8,
     author = {I. V. Protasov},
     title = {A theorem of {Mac} {Lane}},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {40--41},
     publisher = {mathdoc},
     number = {5},
     year = {1980},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_1980_5_a8/}
}