lkbib searches bibliographic databases for references that contain the
keys key ... and prints any references found on the standard output.
lkbib will search any databases given by -p options, and then a
default database. The default database is taken from the REFER
environment variable if it is set, otherwise it is
/usr/dict/papers/Ind. For each database filename to be searched,
if an index filename.i created by indxbib(1) exists, then it
will be searched instead; each index can cover multiple databases.