usage: /usr/bin/refer [-bCenPRS] [-aN] [-cXYZ] [-fN] [-iXYZ] [-kX] [-lM,N] [-p db-file] [-sXYZ] [-tN] [-Bl.m] [file ...]
usage: /usr/bin/refer {-v | --version}
usage: /usr/bin/refer --help

GNU refer is a troff(1) preprocessor that prepares bibliographic
citations by looking up keywords specified in a roff(7) document,
obviating the need to type such annotations, and permitting the
citation style in formatted output to be altered independently and
systematically.  See the refer(1) manual page.