\documentclass[12pt]{article}
\usepackage{a4}
%\usepackage[german]{babel}
%\usepackage[utf8]{inputenc}
\usepackage{amsmath}
\usepackage{ifthen}
\usepackage{float}
\usepackage{graphicx}
\usepackage{wrapfig}
\addtolength{\topmargin}{-10mm}
\addtolength{\textheight}{10mm}
\newcommand\x{0.8}

\sloppy

\setlength{\parindent}{0pt}
\setlength{\parskip}{5pt plus 2pt minus 1pt}

\usepackage[backend=bibtex,citestyle=verbose-ibid]{biblatex}
%\usepackage[backend=bibtex,citestyle=authoryear]{biblatex}
\addbibresource{Landau_Damping.bib}
%\renewcommand{\thefootnote}{\fnsymbol{footnote}}


\renewcommand{\topfraction}{1}
\renewcommand{\bottomfraction}{1}
\renewcommand{\dbltopfraction}{1}
\renewcommand{\floatpagefraction}{1}
\renewcommand{\textfraction}{0}
\renewcommand{\floatsep}{0pt}
\renewcommand{\dblfloatsep}{0pt}

%\input{mysty/prespan}
\newcommand{\vphase}{v_\vph}
\newcommand{\nee}{{n_e}}
\newcommand{\nii}{{n_i}}
\newcommand{\hn}{{\hat{n}}}
\newcommand{\hm}{{\hat{m}}}
\newcommand{\hv}{{\hat{v}}}
\newcommand{\hu}{{\hat{u}}}
\newcommand{\hf}{{\hat{f}}}
\newcommand{\hE}{{\hat{E}}}
\newcommand{\fa}{f_\alpha}
\newcommand{\na}{n_\alpha}
\newcommand{\tv}{\tilde v}
\newcommand{\tu}{\tilde u}
\newcommand{\infint}{\int_{-\infty}^\infty}
\newcommand{\intL}{\frac{1}{L}\int_{-L/2}^{L/2}}
\newcommand{\imag}{\mathrm{Im}}
\newcommand{\real}{\mathrm{Re}}
\input{prespan}

\begin{document}

\include{lecture_1}
\include{lecture_2}
%\include{lecture_first}

\end{document}

