Problem with citation number when using the cite package

Question

I was using the cite package and encountered a problem with it. The citation number sometimes remains "[?]"; even after several compiling cycles. Here is MWE and its outcome:

\documentclass{article}
\usepackage{cite}

\begin{document}
This is a MWE. This citation~\cite{foo} works correctly but this one~\cite{bib: bar} doesn't.

\begin{thebibliography}{2}
\bibitem{foo} foo
\bibitem{bib: bar} bar
\end{thebibliography}

\end{document}

It seems this problem occurs when \bibitem's parameter includes space like \bibitem{bib: bar} bar.

Can anyone solve this problem?

P.S. Further information such as an solution without abondoning my habit would be appreciated.

Answer 1

The Problem is that \cite eats the spacetokens when writing to the main auxiliary file; i.e., even if you say \cite{bib: bar} the resulting entry in the .aux would look like \citation{bib:bar}. But, when the engine is looking for \bibcite{bib:bar}... it won't find anything because \bibitem preserves all the spaces in the input.

You can leave the citations in the desired form, e.g. \cite{bib: bar} if you don't want to abandon your labeling habit, but you have to write \bibitem{bib:bar} ... in the thebibliography environment:

\documentclass{article}
\usepackage{cite}

\begin{document}
This is a MWE. This citation~\cite{foo} works correctly and this one~\cite{bib: bar} too, though there is a space in between the label name. 

\begin{thebibliography}{2}
\bibitem{foo} foo
\bibitem{bib:bar} bar
\end{thebibliography}
\end{document}