@article{TMF_1981_48_2_a6,
     author = {M. Datta and N. P. Klepikov},
     title = {Relativistic centers of mass and clustering},
     journal = {Teoreti\v{c}eska\^a i matemati\v{c}eska\^a fizika},
     pages = {210--215},
     publisher = {mathdoc},
     volume = {48},
     number = {2},
     year = {1981},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TMF_1981_48_2_a6/}
}