Physics Letters A
Physics Letters A > 2003 > 311 > 1 > 53-59
Physics Letters A > 2003 > 313 > 4 > 316-324
Physics Letters A > 2003 > 315 > 1-2 > 136-142
Physics Letters A > 2003 > 316 > 1-2 > 118-121
Physics Letters A > 2003 > 319 > 1-2 > 85-88