Dynamics in Minkowski space is discussed in terms of an eight-parameter extended Galilei group, a subgroup of the Poincar\'e group. This method---Galilean subdynamics---is developed and discussed in detail and applied to the construction of two explicit models having four-point amplitudes of the Veneziano type. There are no difficulties with unphysical states.
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Biedenharn et al. (1974) studied this question.
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