\providecommand{\bysame}{\leavevmode\hbox to3em{\hrulefill}\thinspace}
\providecommand{\MR}{\relax\ifhmode\unskip\space\fi MR }
% \MRhref is called by the amsart/book/proc definition of \MR.
\providecommand{\MRhref}[2]{%
  \href{http://www.ams.org/mathscinet-getitem?mr=#1}{#2}
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\begin{thebibliography}{DD09}

\bibitem[DD09]{dokchitser:parity}
T.~Dokchitser and V.~Dokchitser, \emph{Root numbers and parity of ranks of
  elliptic curves}, \url{http://arxiv.org/abs/0906.1815}.

\end{thebibliography}