About 10 years ago I wrote a perl script called "bibweb" which uses <a href="http://www.ams.org/mathscinet/index.html">MathSciNet</a> to produce bibtex entries for references.  If you have access to MathSciNet and you run

    bibweb -c 'hartshorne;algebraic-geometry'

then one of its answers is

    @book {MR0463157,
        AUTHOR = {Hartshorne, Robin},
         TITLE = {Algebraic geometry},
          NOTE = {Graduate Texts in Mathematics, No. 52},
     PUBLISHER = {Springer-Verlag},
       ADDRESS = {New York},
          YEAR = {1977},
         PAGES = {xvi+496},
          ISBN = {0-387-90244-9},
       MRCLASS = {14-01},
      MRNUMBER = {MR0463157 (57 \#3116)},
    MRREVIEWER = {Robert Speiser},
    }

It's not perfect, but it works for me. Download it at <a href="http://www.math.washington.edu/~palmieri/bibweb.php">http://www.math.washington.edu/~palmieri/bibweb.php</a>.  It's free, so satisfaction guaranteed or double your money back.