website reference for building R packages

Hi R People:

A few weeks ago, someone put a link to a website for "how to" for building R 
packages.  It was very nice.

But of course, I have misplaced the link.  Does anyone still have that, 
please?

It was someone from the University of Chicago, I believe.

Thanks in advance.

Sincerely,
Laura Holt
mailto: lauraholt_983 at hotmail.com