Physics Letters A
Physics Letters A > 2006 > 349 > 1-4 > 98-103
Physics Letters A > 2006 > 356 > 4-5 > 371-375
Physics Letters A > 2006 > 357 > 2 > 97-100
Physics Letters A > 2006 > 358 > 2 > 100-104
Physics Letters A > 2006 > 359 > 5 > 402-405