Different numbers of self-gravitating particles (in different types of periodic motion) are most likely to generate very different shapes of gravitational waves, some of which, however, can be accidentally almost the same. One such example is a binary and three-body system for Lagrange's solution. To track the evolution of these similar wave forms, we define a chirp mass to the triple system. Thereby, we show that the quadrupole wave forms cannot distinguish the sources. It is suggested that wave forms with higher lth multipoles will be important for classification of them (with a conjecture of l<or=N for N particles).