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3. L. Lanz, L. A. Lugiato andG. Ramella:On the quantum-mechanical treatment of decaying nonrelativistic systems, to appear inInt. Journ. Theor. Phys.;L. Lanz, L. A. Lugiato, G. Ramella andA. Sabbadini:The embedding of unstable nonrelativistic particles into Galilean quantum field theories, to appear inInt. Journ. Theor. Phys.
4. L. Lanz andL. A. Lugiato:On the particle level of Galilean quantum field theories, submitted for publication.
5. J. M. Levy-Leblond:Comm. Math. Phys.,4, 57 (1967).