\documentclass{article}
\usepackage[utf8]{vietnam}
\include{sampleformat}

%PACKAGEOPTIONS
\usepackage{arev}
\pdfmapfile{+arevvn.map}
\begin{document}
\fontencoding{T5}\selectfont

\include{textfragment1}
% \include{textfragment}

\end{document}