Answers for "cite in order of appearance latex bibtex"

latex reference in order of appearance

documentclass[12pt]{article}
usepackage[sorting=none]{biblatex}
bibliography{journals,phd-references} % Where journals.bib and phd-references.bib are BibTeX databases
begin{document}
cite{robertson2007}
cite{earnshaw1842}
printbibliography
end{document}