About 10 years ago I wrote a perl script called "bibweb" which uses MathSciNetMathSciNet 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 https://github.com/jhpalmieri/bibweb. It's free, so satisfaction guaranteed or double your money back.