Citing the source of an equation?

Question

I cant find a good way of adding a \cite to an equation. I'd like to give a reference to the equation's source, but I can't figure out how to typeset it nicely. If I include it in with the equation itself, it pushes the alignment leftwards and feel too much like it's invading the equation's space. I've tried putting an \hfill\cite{example} on the line after the equation, but there's too much vertical space between the equation and the reference.

I'd love to know if there's a commonly accepted way of doing this that I haven't managed to find. Failing that, if anyone has any not-too-inelegant compromises, that'd be great too.

Answer 1

You shouldn't add the references inside the equation IMO, but outside as in this code:

% arara: pdflatex: {synctex: yes}
% arara: biber
% arara: pdflatex: {synctex: yes}
% arara: pdflatex: {synctex: yes}
%
\documentclass{article}
\usepackage{filecontents}
\usepackage[backend=biber]{biblatex}
\addbibresource{biblatex-examples.bib}
\begin{document}
From the famous inequality math relation~\cite{companion}
\begin{equation}
  y \neq x
\end{equation}
%
Or you can also say:
\begin{equation}
  y \neq x
\end{equation}
as proved by~\cite{companion} 
\printbibliography
\end{document}

Thus leaving equations to themselves. This reduces the confusion between the parameters and the citation number. (Equations are equations - Don't put something else inside :-))