% monoref -- single-run numbered citations
% Compile once with LuaLaTeX:  lualatex 07-citations.tex
%
% Every \cite below appears BEFORE the bibliography, so all of them are
% forward references; monoref patches the numbers at the end of the run.
% Works with a hand-written thebibliography (no BibTeX run needed).
\documentclass{article}
\usepackage{monoref}

\begin{document}

\section{Citing forward}\label{sec:cite}
A single citation~\cite{knuth}, a repeat of it~\cite{knuth}, a
different one with a note~\cite[Chapter~2]{lamport}, and a multi-key
list~\cite{knuth,luatex,lamport} (source order, as in plain \LaTeX).
The bibliography itself starts on page~\pageref{bib:start}.

\begin{thebibliography}{9}\label{bib:start}
\bibitem{knuth} D.~E. Knuth. \emph{The \TeX book}. Addison-Wesley, 1986.
\bibitem{lamport} L.~Lamport. \emph{\LaTeX: A Document Preparation
  System}. Addison-Wesley, 2nd edition, 1994.
\bibitem{luatex} LuaTeX development team. \emph{LuaTeX Reference
  Manual}, 2024.
\end{thebibliography}

\end{document}