# How to make the style of subsection and subsubsection identical?

I'm observing a strange behavior in the subsection/subsubsection titles. Their styles look different. Is there a simple way to fix it?

\documentclass{amsbook}

\usepackage[english]{babel}
\usepackage{blindtext}

\begin{document}

\blinddocument

\end{document}

• Also, what exactly do you mean by "number size"? – ℝaphink Jul 11 '11 at 5:36
• The size of the subsection number vs the size of the subsubsection number. – user02138 Jul 11 '11 at 5:39
• @user: I have edited your question, now does it reflect what you wanted to say? Don't forget to remove your unnecessary comments above. – xport Jul 11 '11 at 5:52
• Yes, xport, thank you! I was more concerned about the numbers having different height, but this is fine. – user02138 Jul 11 '11 at 5:52

this makes the \subsubsection looks like a \subsection

\documentclass{amsbook}
\makeatletter
\def\subsubsection{\@startsection{subsubsection}{3}%
\normalparindent{.5\linespacing\@plus.7\linespacing}{-.5em}%
{\normalfont\bfseries}}
\makeatother
\usepackage[english]{babel}
\usepackage{blindtext}

\begin{document}
\blinddocument
\end{document}