RequirePackage{filecontents}
begin{filecontents}{mybib.bib}
@misc{bb09 , Author = "Blah and Blue", year = 2009}
end{filecontents}

documentclass{article}
bibliographystyle{alpha}
usepackage{natbib}
usepackage[svgnames]{xcolor} for 'DarkGreen' color
usepackage[colorlinks,allcolors=DarkGreen]{hyperref}

begin{document}
noindent
cite{bb09}, cite[Proposition~1.8]{bb09}
bibliography{mybib}
end{document}