  The general form of solutions for parameters of interfering Breit-Wigner
resonances is found. The number of solutions is determined by the properties of
roots of corresponding characteristic equation and does not exceed $2^{N-1}$,
where $N$ is the number of resonances. For resonances of more complicated form,
provided that their amplitudes satisfy certain conditions, for any $N\ge2$
multiple solutions also exist.
