@article{TMF_1973_15_3_a12,
     author = {N. A. Potapkov},
     title = {Perturbation theory with variational parameter. {Inequalities} and estimates for the free energy},
     journal = {Teoreti\v{c}eska\^a i matemati\v{c}eska\^a fizika},
     pages = {407--416},
     publisher = {mathdoc},
     volume = {15},
     number = {3},
     year = {1973},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TMF_1973_15_3_a12/}
}