Random asterisk when using BibTeX and res.cls

The problem comes from the line

\section*{\refname}

used inside the thebibliography environment as defined in article.cls (the base document class for res.cls). To prevent the asterisk, add the following lines to the preamble:

\makeatletter
\renewenvironment{thebibliography}[1]
     {\list{\@biblabel{\@arabic\c@enumiv}}%
           {\settowidth\labelwidth{\@biblabel{#1}}%
            \leftmargin\labelwidth
            \advance\leftmargin\labelsep
            \@openbib@code
            \usecounter{enumiv}%
            \let\p@enumiv\@empty
            \renewcommand\theenumiv{\@arabic\c@enumiv}}%
      \sloppy
      \clubpenalty4000
      \@clubpenalty \clubpenalty
      \widowpenalty4000%
      \sfcode`\.\@m}
     {\def\@noitemerr
       {\@latex@warning{Empty `thebibliography' environment}}%
      \endlist}
\makeatother

Discovered this answer purely accidentally. If you use this answer (by the same author as the accepted answer in this question!) to suppress the "References" title that \bibliographygenerates, then this problem is automatically (auto-magically perhaps!) fixed. So, the overall solution looks cleaner. In the spirit of Tex.SE, am reproducing part of the answer here:

Add these lines to the preamble:

\usepackage{etoolbox}
\patchcmd{\thebibliography}{\section*{\refname}}{}{}{}