Springer-Verlag Copyright

The copyright for the following article was transferred to Springer-Verlag at the time of publication:

    David N. Williams, "Difficulty with a Kinematic Concept of Unstable Particles: the Sz.-Nagy Extension and the Matthews-Salam-Zwanziger Representation", Commun. Math. Phys. 21, 314–333 (1971),
    Copyright © 1971 Springer-Verlag

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