If you forget to use
in your document (or, less likely, any
command), BibTeX will issue an error message. Because BibTeX
can be used with any program, not just LaTeX, the error messages
refer to the internal commands read by BibTeX (from the .aux
file), rather than the user-level commands described above.
Here is a table showing internal commands mentioned in the BibTeX errors, and the corresponding user-level commands.
For example, if your document has no
command, BibTeX complains as follows:
I found no \bibstyle command---while reading file document.aux