SIGMA is an open access journal. Nevertheless, despite open access, we do not charge authors for publication.
SIGMA is a non-profit, volunteer-run project. The journal has no
steady sources of funding and operates solely on the basis of the
editors' enthusiasm. All work in editing, copy-proofing etc. is done
by volunteers on gratuitous basis.
So, if you (or your organization) would like to support us financially, please contact us.