1. Bardeen W A, Charnowicz M S, Drell S D, Weinstein M and Yan T M 1975Phys. Rev. D11 1904
2. Barik N and Jena S N 1981Phys. Rev. D22 1704
3. Bereteskii V B, Lifshitz E M and Pitaevski V 1971Relativistic quantum theory (Oxford: Pergamon) p. 280
4. Biswal K and Misra S P 1982Phys. Rev. D26 1175
5. Bhaduri R and Brack M 1982Phys. Rev. D25 1443