Oblivious signatures

Hello
I am looking for a copy of "oblivious Signatures" by L Chen, Computing
Security ESORICS 94. Can any one tell me where I can get a copy?
On a more general topic other then as a foundation for other protocls
what purpose to oblivious signatures have? How does Bob know that the
N messages he has to choose from are not identical?
    Any comments on this matter would be appreciated
     Regards
       David