Cryptology ePrint Archive: BibTeX Citation of Report 2011/666

@misc{cryptoeprint:2011:666,
    author = {Eyal Z. Goren  and Kristin E. Lauter},
    title = {A Gross-Zagier formula for quaternion algebras over totally real fields},
    howpublished = {Cryptology ePrint Archive, Report 2011/666},
    year = {2011},
    note = {\url{http://eprint.iacr.org/}},
}

You will need the url.sty package (comes with most LaTeX installations) for the last line. Otherwise, remove the \url command.