To use, add `company-reftex-labels' and `company-reftex-citations' to `company-backends' in the buffers where you want it activated. The major mode must be derived from `latex-mode', and `reftex-mode' must be switched on for them to work. - `company-reftex-labels' will trigger inside forms like \ref{}, \eqref{}, \auroref{}, etc. - `company-reftex-citations' will trigger inside cite{}. These backends collect data from RefTeX, which is very powerful. Citations from external bibtex files should be found automatically. In multi-file documents, make sure `TeX-master' is set appropriately.