  The calculation of an amplitude involving resonance production is presented.
This calculation employs for the resonance state a relativistic Gamow vector.
It is used for investigating the question of compatibility of the relativistic
Gamow vectors kinematics, defined by real 4-velocities and complex mass, with
the stable particle kinematics; or in other words, the integration of the Gamow
vectors with the conventional Dirac bra-ket formalism. The calculation
demonstrates a consistent framework comprising stable and Gamow vectors.
