The paper is Phys. Rev. Lett. 96, 060504 (2006) (links to abstract - sorry Ivan but the physorg write-up is awful)
and it is available for free as an e-print at arXiv /quant-ph:
A very interesting development, I'm yet to read the paper (need more coffee for that). Anyone who's new to the subject of multipartite entanglement, I recommend the very recent review by Eisert and Gross:
hey im new to this, but how do i open those pdf's?
Do you have Acrobat Reader installed? (it's free). Then clicking on a pdf will open it up automatically for you.
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