@article{ZNSL_1979_94_a14,
     author = {A. V. Yakovlev},
     title = {Homological algebra in {pre-Abelian} categories},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {131--141},
     publisher = {mathdoc},
     volume = {94},
     year = {1979},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_1979_94_a14/}
}