# Manually created bibliography keeps giving citation undefined

Sample code:

\documentclass[a4paper,12pt]{article}

\usepackage{graphicx}
\usepackage[text={16cm,25cm}]{geometry}
\usepackage{biblatex}
\begin{document}

\title{stuff}
\maketitle

\section{Section 1}
Random text \cite{citation1}

\begin{thebibliography}{99}

\bibitem{citation1} Citation things (2017)

\end{thebibliography}

\end{document}


I'm trying to create a short manual bibliography and all my references appear correctly where they should be in the References section, but whenever I try to cite them in the main text, I always get a "LaTeX Warning: Citation 'X' on page Y undefined on input line Z."

I've tried looking up how to set such a bibliography up and I can see no difference between what I've done and what they say to do. This is the first time I've ever tried this so I'm probably missing something painfully obvious.

• Don't load the biblatex package if you want to do this. It redefines \cite. – Ulrike Fischer Nov 9 '17 at 17:45
• Welcome to TeX.SX!. Well I think you're confused because in the preamble you're calling the biblatex package, but in the document you're using the manual way for cite, the worst choice IMO, mainly if you handle a large volume of references in your document (more than 10 for me). – Aradnix Nov 9 '17 at 19:20