@article{PFMT_2015_1_a1,
     author = {V. N. Kapshai and M. S. Danilchenko and Yu. A. Grishechkin},
     title = {Covariant equations and resonance states of two-particle systems with $\delta$-function potentials},
     journal = {Problemy fiziki, matematiki i tehniki},
     pages = {11--15},
     publisher = {mathdoc},
     number = {1},
     year = {2015},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/PFMT_2015_1_a1/}
}