Bibliography & Citations

Why Citations Show as [?] in LaTeX

Seeing [?] instead of citation numbers means LaTeX can't find the reference. This is usually a compilation or file path issue.

Compile in Correct Order

BibTeX needs multiple compile passes:

% Run these commands in order:
pdflatex document.tex   % Creates .aux file
bibtex document         % Processes citations
pdflatex document.tex   % Inserts citations
pdflatex document.tex   % Fixes page numbers

% For BibLaTeX with Biber:
pdflatex document.tex
biber document
pdflatex document.tex

Check Citation Key

Key in \cite must match .bib file exactly:

% In references.bib:
@article{Smith2020,  % Key is "Smith2020"
  author = {...},
  ...
}

% In document - must match exactly (case-sensitive):
\cite{Smith2020}  % Correct
\cite{smith2020}  % WRONG - different case!

Verify .bib File Path

Make sure LaTeX can find your bibliography:

% If .bib is in same folder:
\bibliography{references}  % Not references.bib!

% If in subfolder:
\bibliography{./bib/references}

% Check for typos in filename!

Check for BibTeX Errors

Look at the .blg log file:

% Open document.blg for BibTeX errors:
I found no database files

% This means wrong path or filename
% Also check for syntax errors in .bib entries

💡 Tips

•In Overleaf, use the Logs panel to see BibTeX errors
•Delete auxiliary files (.aux, .bbl, .blg) and recompile
•Use \nocite{*} to include all references even if not cited

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