# Citing references while supplying additional information

I'm trying to cite a reference as in the following picture

But all I'm getting is:

I'm using \cite to generate citation call-outs in an "alphabetic" style. Can someone help me please?

• Hi, welcome. \cite[Proposition 1.8]{bour71}? – Torbjørn T. Oct 21 '17 at 22:19
• Do you use biblatex? It has commands for this. – Bernard Oct 21 '17 at 22:23
• I tried using [Proposition 1.8] before, but it's not changing the colour of the square brackets [ and ] :\ – Veridian Oct 21 '17 at 22:25
• Welcome to TeX.SE! Please show us a short, compilable code how you cite and build your bibliography. Do not forget and add one bib entry to your question! – Mensch Oct 21 '17 at 22:34

Something like this?

\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