Exact thermodynamic Casimir forces for an interacting three-dimensional model system in film geometry with free surfacesH. W. Diehl, Daniel Grüneberg, Martin Hasenbusch, Alfred Hucht, Sergei B. Rutkevich and Felix M. SchmidtEPL, 100 1 (2012) 10004DOI: https://doi.org/10.1209/0295-5075/100/10004