@article{ISU_2020_20_4_a2,
     author = {Ya. A. Kopylov},
     title = {On some diagram assertions in preabelian and $P$-semi-abelian categories},
     journal = {Izvestiya of Saratov University. Mathematics. Mechanics. Informatics},
     pages = {434--443},
     publisher = {mathdoc},
     volume = {20},
     number = {4},
     year = {2020},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/ISU_2020_20_4_a2/}
}