I like to acknowledge authors of the software I'm using in my work. I realize that it isn't straight forward to assign authorship to open-source software. Thus my question is: What do you think is the best way to acknowledge Eigen in scientific publications?

A couple of ideas comes to mind:

1) Referencing Eigen in-line with a footnote link to the website.
2) Mention Eigen along with the website in the Acknowledgement section.
3) Use a provided reference to Eigen or some first-author (e.g. like matplotlib: http://matplotlib.org/citing.html).

I'm open to any suggestion as long as it follows the general guidelines of scientific journals.

http://eigen.tuxfamily.org/index.php?title=BibTeX

Thanks!