please refer to the M-M.E.S.S. toolbox by at least its acronym and the version number. The core Copyright holders are Jens Saak, Martin Köhler and Peter Benner. They should be given as the authors in a citation. The project is frequently updated on Zenodo and every stable release will receive a DOI for proper citation there. The DOI for this version and a sample BibTeX entry can be found below.
The DOI for version 2.0.1 is 10.5281/zenodo.3606345
@Misc{SaaKB19-mmess-2.0.1,
key = {MMESS},
author = {Saak, J. and K\"{o}hler, M. and Benner, P.},
title = {{M-M.E.S.S.}-2.0.1 -- The Matrix Equations Sparse
Solvers library},
howpublished = {DOI:10.5281/zenodo.3606345},
month = feb,
year = 2020,
note = {see also:\url{www.mpi-magdeburg.mpg.de/projects/mess}}
}