refer is a program for managing bibliographic references, and citing them in troff documents. It is implemented as a troff preprocessor.
refer was written by Mike E. Lesk at Bell Laboratories [1] in or before 1978, and is now available as part of most Unix-like operating systems. A free reimplementation exists as part of the groff package.
refer works with a reference file, a text file where the author lists works to which she might want to refer to. One such reference (to an article in a journal in this case) might look like:
%A Brian W. Kernighan %A Lorinda L. Cherry %T A System for Typesetting Mathematics %J J. Comm. ACM %V 18 %N 3 %D March 1978 %P 151-157 %K eqn
The author then can refer to it in her troff document by listing keywords which uniquely match this reference:
.[ kernighan cherry eqn .]
refer sees little use today, primarily because troff itself is not used much for longer technical writing that might need software support for reference and citation management.
Comparison of reference management software