@article{TMF_1979_41_2_a9,
     author = {A. I. Ivanov and G. S. Lomakin and O. A. Ponomarev},
     title = {Investigation of systems with quadratic interaction by the method of functional derivatives},
     journal = {Teoreti\v{c}eska\^a i matemati\v{c}eska\^a fizika},
     pages = {273--284},
     publisher = {mathdoc},
     volume = {41},
     number = {2},
     year = {1979},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TMF_1979_41_2_a9/}
}