LaTeX: How to add a prefix to `natbib` references and bibliography with `numbers` citation style and without `biblatex`?

main.tex

\documentclass{your_thesis_class}

\usepackage[utf8x]{inputenc} % <--- required by Inkscape generated pdf_tex figures. biblatex won't work with these
\usepackage[numbers]{natbib}
% \setcitestyle{numbers} % <--- if natbib is already included by another package
\usepackage{bibunits} % <--- lets you have a separate bibliography, e.g. your own publications list

\begin{document}

\begin{bibunit}[unsrtnat] % <--- unsrtnat arranges bibliography list in appearance order
\renewcommand\bibsection{\section*{\refname}} % <--- places bibliography in a section instead of a chapter

% Modify the format for this section only
\renewcommand{\citenumfont}[1]{A#1} % <--- Appends letter A to a numbered citation in the text, e.g. generated with \citep{}
\renewcommand{\bibnumfmt}[1]{[A#1]} % <--- Appends letter A to a numbered reference in the bibliography list

\chapter{Publications}

\putbib[references] % <--- generates bibliography list from references.bib file
\end{bibunit}

\end{document}