@article{MZM_1975_17_6_a4,
     author = {A. V. Mikhalev and M. A. Shatalova},
     title = {Free $f$-modules},
     journal = {Matemati\v{c}eskie zametki},
     pages = {873--885},
     publisher = {mathdoc},
     volume = {17},
     number = {6},
     year = {1975},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1975_17_6_a4/}
}