\label{test_level1}
\usepackage{wasysym}

\include{included_level2}

\ref{test_level1}
\ref{test_level2}

\degreeCelsius

\clock

\begin{thebibliography}{9}
\bibitem{texbook}
Donald E. Knuth (1986) \emph{The \TeX{} Book}, Addison-Wesley Professional.

\bibitem{lamport94}
Leslie Lamport (1994) \emph{\LaTeX: a document preparation system}, Addison
Wesley, Massachusetts, 2nd ed.
\end{thebibliography}