Supplementary material to: Finite-size effects in the interfacial   stiffness of rough elastic contacts
  In this supplementary materials section, we provide (i) additional information on the numerical simulations of the main work, (ii) the derivation of all prefactors in the analytical theory, and (iii) unpublished experiments of the contact stiffness of a polymer pressed against a rough substrate. 
Lars Pastewka, Nikolay Prodanov, Boris Lorenz, Martin H. M\"user, Mark   O. Robbins and Bo N. J. Persson
cond-mat.soft