1) Surface phenomena of gradient materials
          Continuum Mech. Thermodyn. (2021)

      The article explains the existence of a crust shell
        on a free surface and of edge beams where patches
        of a free surface meet, independent of any constitutive
        assumptions


        2) The crust shell and the edge beams of third-gradient
           continua in current and referential description
                Acta Mechanica (2023)

         The article investigates the connection between the current and
          the referential representation of free surface boundary conditions
          Moreover, an example shows that the treatment of fictitious cuts
          in the same manner as free surfaces (namely the application of the
          divergence theorem of surfaces without any physical reason) may
          produce  absurd results

     3) Surface tension and reaction stresses of a
          linear incompressible second gradient fluid
            Continuum Mech. Thermodyn. (2021)

     The article contains:
       a) A discussion of boundary conditions and surface tension,
            independent of the constitutive behavior
       b) The investigation of a stirring process with free surface