\begin{thebibliography}{1}

\bibitem{ref3}
PHP Groupe.
\newblock Xml dom manipulation, unknown unknown.
\newblock \url{http://php.net/manual/en/book.dom.php}.

\bibitem{ref1}
Pradeep Khodke.
\newblock Tutorial: Php login and registration script with pdo and oop, April
  2015.
\newblock
  \url{http://www.codingcage.com/2015/04/php-login-and-registration-script-with.html}.

\bibitem{ref5}
Jennifer Kyrnin.
\newblock How to use php to force a file download, Januar 2017.
\newblock \url{http://webdesign.about.com/od/php/ht/force_download.htm}.

\bibitem{ref4}
Virgilio~Favero Neto.
\newblock How to save xml using php, August 2010.
\newblock
  \url{http://stackoverflow.com/questions/3552755/how-to-save-xml-using-php#3552794}.

\bibitem{ref2}
Richard Stibbard.
\newblock Mysql pdo tutorial, August 2014.
\newblock
  \url{https://youtu.be/e0ssKVEISbQ?list=PLz_6dB4PItBEQEbVSAt6vrTOACQZD1K1E}.

\end{thebibliography}