\documentclass[11pt,oneside]{book}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\title{Per-chapter bibliographies with bibunits}
\usepackage[a4paper]{geometry}
\usepackage[sectionbib]{natbib}
\usepackage{bibunits}
%\defaultbibliographystyle{unsrtnat} %% For numerical citations remember to pass "numbers" option to natbib
\defaultbibliographystyle{dcu}
\defaultbibliography{sample}
%%% Uncomment if you change the bibliography heading/title
% \renewcommand{\bibname}{References}
%%% Uncomment if you want to include the bibliographies at the end of each chapter in the table of contents.
% \usepackage[nottoc]{tocbibind}
\begin{document}
%% Can only be called _after_ \begin{document}
\bibliographyunit[\chapter]
\frontmatter
\chapter*{Abstract}
This is \emph{not} a full thesis template! It only demonstrates how to create per-chapter references using the \texttt{bibunits} package with BibTeX. (Do not use with BibLaTeX!)
There are two possible ways to do this. One is by calling \verb|\bibliographyunit[\chapter]| after \verb|\begin{document}|, so that \texttt{bibunits} will automatically treat each chapter as a reference/bibliography unit. (This file uses this approach.) Another way is to put \verb|\begin{bibunit}...\end{bibunit}| around each chapter, or around arbitrary blocks of text, which may be useful if you need to put the references at the end of each \textit{part} instead of chapter! (The file \texttt{alt.tex} uses this approach.)
If compiling on your own machine, run \texttt{bibtex} on \emph{each} generated \texttt{.aux} file, before running \texttt{pdflatex} twice more. (These are done automatically on Overleaf.)
When using \texttt{bibunits}, you may get a warning \verb|I found no \citation commands| if all your chapters are in their own \texttt{.tex} files and there is no \verb|\cite| commands in the main \texttt{.tex} file itself. This warning can be ignored if that's how you intended things to be anyway.
\tableofcontents
\mainmatter
%%%%%%%%%%%%%%%%%%%%%%%%%%
\chapter{First Chapter}
\section{Section Heading}
Here's a citation! \citep{latex:companion}
\putbib
%% You can use \pubib[anotherfile] if citations in this chapter is from anotherfile.bib instead
%%%%%%%%%%%%%%%%%%%%%%%%%%%
\chapter{Second Chapter}
\section{Section Heading}
Here's another citation! \citep{lshort}
\putbib
\backmatter
%% A list of publications can be created using this approach
\chapter*{List of Publications}
\addcontentsline{toc}{chapter}{List of Publications}
\nocite{lim:etal:kdtei:2016,markdown:overleaf} % .bib keys of your own publications
{\renewcommand{\bibsection}{}
\putbib
}
\end{document}