I am looking for any reference on Wigner's classification of irreducible representations of the Poincaré group. I know the classification, but is there any reference where the representations are constructed and explained. This classification gives the different spin particles in Quantum mechanics. Thanks.
Edit (Qiaochu Yuan, 7/12/11): I am also interested in the answer to this question and unsatisfied with the current answer, so I have offered a bounty. I don't currently have institutional access to Wigner's original paper and in any case find it a little difficult to read, and would appreciate a modern, thorough, mathematical account.