The thing to do here is write a function that will take a bibtex key, and
loop through your directories to find the pdf, and then return the full
path to the pdf. Then customize the variable org-ref-get-pdf-filename-function
to point to that function.

https://github.com/jkitchin/org-ref/blob/master/org-ref.el#L122

Out of the box, org-ref expects all the pdfs to be named key.pdf and to be
in a single directory. That is partly due to this library
https://github.com/jkitchin/org-ref/blob/master/doi-utils.el which
downloads pdfs for you from a doi in that format.

John

-----------------------------------
Professor John Kitchin
Doherty Hall A207F
Department of Chemical Engineering
Carnegie Mellon University
Pittsburgh, PA 15213
412-268-7803
@johnkitchin
http://kitchingroup.cheme.cmu.edu


On Wed, May 13, 2015 at 3:00 PM, Michael Giepen <mgiepen@uni-bonn.de> wrote:

> Hello,
>
> I just cannot get org-ref to accept various directories:
>
> I tried
>
> (setq org-ref-pdf-directory (quote (
> "/home/mcg/thesis/library/folder1/"
> "/home/mcg/thesis/library/folder2/"
> "/home/mcg/thesis/library/folder3/"
> )))
>
>
> It would also suffice if I could include subdirectories of
> .../thesis/library/
>
>
>
>