@article{UZKU_2011_153_3_a2,
     author = {A. M. Baranov},
     title = {The {Petrov} algebraic classification and phase transitions in gravitational fields},
     journal = {U\v{c}\"enye zapiski Kazanskogo universiteta. Seri\^a Fiziko-matemati\v{c}eskie nauki},
     pages = {29--41},
     publisher = {mathdoc},
     volume = {153},
     number = {3},
     year = {2011},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/UZKU_2011_153_3_a2/}
}