documentclass{book}
usepackage{graphicx}
usepackage{subfig}%
captionsetup[subfloat]{%
font=normalsize,labelformat=parens,labelsep=space}


begin{document}

begin{figure}
subfloat[label{fig:eBoxEndowment}]{includegraphics[width=0.47columnwidth]{10821_001_fig_001a.pdf}}hfill
subfloat[label{fig:eBoxPrices}]{includegraphics[width=0.47columnwidth]{10821_001_fig_001b.pdf}}
caption{The Edgeworth box. The axes along which the endowment and
}
end{figure}

end{document}