Rules / OutputUnresolved reference in the PDFThe PDF shows "??" where a figure, table, section or equation number belongs.Fix‸Make sure every \ref has a matching \label (same spelling), then rebuild with latexmk.Other output rulesUndefined citationUndefined referenceBibliography not builtBibliography out of dateLaTeX needs another runEmpty bibliographyFigure file not foundLabel defined twice