Come mi hai suggerito…
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\documentclass[a4paper,oneside,12pt]{book}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage[italian]{babel}
\usepackage{microtype}
\usepackage{geometry}
\geometry{textwidth=140mm,textheight=200mm,heightrounded,footskip=20mm}
% \usepackage[sf]{titlesec}
\usepackage{verbatim}
\usepackage{amsmath}
\usepackage{amssymb}
%\usepackage{latexsym}
%—-Bibliografia————————
\usepackage[babel]{csquotes}
\usepackage[useprefix, style=numeric]{biblatex}
\bibliography{MaterialeStartEnd/Bibliografia}
\usepackage{mathpazo}
%\usepackage{txfonts
%\usepackage{tgtermes}
\usepackage{setspace}
\usepackage{graphicx}
\usepackage{subfig}
\usepackage{booktabs}
\usepackage{tabularx}
\usepackage[table,svgnames,dvipsnames,x11names]{xcolor}
\doublespacing
% PER I SISTEMI DI EQUAZIONI
\newenvironment{sistema}%
{\left\lbrace\begin{array}{@{}l@{}}}%
{\end{array}\right.}
\includeonly {MaterialeStartEnd/Introduzione}
\begin{document}
\include{MaterialeStartEnd/Dedica}
\pagenumbering{roman}
\include{MaterialeStartEnd/Indice}
\pagestyle{headings}
\pagenumbering{arabic}
\include{MaterialeStartEnd/Introduzione}
\include{Capitoli/Capitolo1}
\include{Capitoli/Capitolo2}
\include{Capitoli/Capitolo3}
\include{MaterialeStartEnd/Conclusioni}
\addcontentsline{toc}{chapter}{\bibname}
\printbibliography
\include {MaterialeStartEnd/Ringraziamenti}
\end{document}
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