Physical Review Letters"Hidden Linear Momentum" Related to the α→·E→ Term for a Dirac-Electron Wave Packet in an Electric FieldW. ShockleyPublished Feb 12, 1968• 49 citationsPublisherAbstractReceived 29 September 1967DOI:https://doi.org/10.1103/PhysRevLett.20.343©1968 American Physical SocietyDOI10.1103/physrevlett.20.343