@article{TMF_2002_130_1_a3,
     author = {\'E. A. Arinstein},
     title = {Perturbation {Theory} for {Density} {Matrices} and the {Thermodynamic} {Potential} of {a~Quantum} {System}},
     journal = {Teoreti\v{c}eska\^a i matemati\v{c}eska\^a fizika},
     pages = {54--63},
     publisher = {mathdoc},
     volume = {130},
     number = {1},
     year = {2002},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TMF_2002_130_1_a3/}
}