@article{ISU_2010_10_1_a13,
     author = {M. B. Abrosimov and A. A. Dolgov},
     title = {On directed acyclic exact extensions},
     journal = {Izvestiya of Saratov University. Mathematics. Mechanics. Informatics},
     pages = {83--88},
     publisher = {mathdoc},
     volume = {10},
     number = {1},
     year = {2010},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ISU_2010_10_1_a13/}
}