  The complete spectrum of plasmons of the two interpenetrating plasma streams
is found in a closed analytic form. The orientation of the wave vector with
respect to the stream direction is arbitrary and the plasmas, which are assumed
to be collisionless and spatially homogeneous, can be nonrelativistic,
relativistic or even ultrarelativistic. Our results apply to the
electromagnetic plasma of electrons and passive ions and to the quark-gluon
plasma governed by QCD.
