document.tex

\documentclass[12pt,a4paper]{book}
%
\input{includes}
\input{definitions}
%
\begin{document}
\maketitle
\tableofcontents
%
% TODO:
%   units package?
%   exercises in script?
%   parts of TAOCP?
%
\newpage

\switch%
\case{\equals{\languagename}{ngerman}}%
  \selectlanguage{ngerman}%
  \input{titlepage_de}%
  \input{gdi001_intro_de}%
  \input{gdi002_bits_de}%
  \input{gdi003_logic_de}%
  \input{gdi004_set_theory_de}%
  \input{gdi005_turing_de}%
  \input{gdi006_graph_de}%
  \input{gdi007_encoding_de}%
  \input{gdi008_abstraction_de}%
  \input{gdi009_landau_de}%
  \input{gdi010_algo_de}%
  \input{gdi011_complexity_de}%
  \input{gdi012_lang_de}%
  \input{gdi013_people_de}%
  \bibliography{bibliography_de}%
%
\case{\equals{\languagename}{english}}%
  \selectlanguage{english}%
  \input{titlepage_en}%
  \input{gdi001_intro_en}%
  \input{gdi002_bits_en}%
  \input{gdi003_logic_en}%
  \input{gdi004_set_theory_en}%
  \input{gdi005_turing_en}%
  \input{gdi006_graph_en}%
  \input{gdi007_encoding_en}%
  \input{gdi008_abstraction_en}%
  \input{gdi009_landau_en}%
  \input{gdi010_algo_en}%
  \input{gdi011_complexity_en}%
  \input{gdi012_lang_en}%
  \input{gdi013_people_en}%
  \bibliography{bibliography_en}%
\otherwise%
  \errmessage{Unknown valid language configured.}
\endswitch%

\bibliographystyle{alpha}
\printindex

\end{document}