Using the tufte-latex package, the tufte-book class replaces the page argument from the cite command with a positioning argument, therefore impariring the possibility of citing pages. Is there a way to go around it an keep citing with pages?
The normal way of using tufte-book without pages is like this:
tufte-mwe.tex :
\documentclass{tufte-book}
\begin{document}
A citation\cite{Tufte2001}.
\bibliography{tufte-mwe}
\bibliographystyle{plainnat}
\end{document}
tufte-mwe.bib:
@BOOK{Tufte2001,
author = {Edward R. Tufte},
title = {The Visual Display of Quantitative Information},
publisher = {Graphics Press},
year = {2001},
address = {Cheshire, Connecticut},
isbn = {0-9613921-4-2}
}
Produces this:

But using cite to insert page numbers like this:
\documentclass{tufte-book}
\begin{document}
A citation\cite[p.50]{Tufte2001}.
\bibliography{tufte-mwe}
\bibliographystyle{plainnat}
\end{document}
Doesn't work and produces this: 
This is because the tufte-book class expects a measure of position and not a page number (to append to the citation) as an argument.
Thanks.
edit: added mwe and precisions
\documentclass{...}and ending with\end{document}. – Oct 09 '14 at 21:45natbibbut I think you can add the pages field in your reference, and then maybe they'll appear in your citation. – Aradnix Oct 10 '14 at 02:28