@article{TMF_1974_21_1_a0,
     author = {A. K. Kazanskii},
     title = {Equations for {Green's} functions obtained from a~variational principle},
     journal = {Teoreti\v{c}eska\^a i matemati\v{c}eska\^a fizika},
     pages = {3--12},
     year = {1974},
     volume = {21},
     number = {1},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TMF_1974_21_1_a0/}
}