Detlev, Buchholz; Summers, Stephen S. (2006). "Scattering in Relativistic Quantum Field Theory: Fundamental Concepts and Tools". Encyclopedia of Mathematical Physics. Academic Press. pp. 456–465. doi:10.1016/B0-12-512666-2/00018-3. ISBN978-0-12-512666-3. S2CID16258638.
Detlev, Buchholz; Summers, Stephen S. (2006). "Scattering in Relativistic Quantum Field Theory: Fundamental Concepts and Tools". Encyclopedia of Mathematical Physics. Academic Press. pp. 456–465. doi:10.1016/B0-12-512666-2/00018-3. ISBN978-0-12-512666-3. S2CID16258638.