Log Message:
Import tex-natbib-8.3 as print/tex-natbib.

This package provides a style with author-year and numbered
references, as well as much detailed of support for other bibliography
use.  Included are versions of the standard BibTeX styles that are
compatible with natbib: plainnat, unsrtnat, and abbrnat.  The
bibliography styles produced by custom-bib are designed from the start
to be compatible with natbib.