\Bibitem{PolGol93} \by V.~V.~Polyakov, A.~V.~Golovin \paper Elastic characteristics of porous materials \jour Prikl. Mekh. Tekh. Fiz. \yr 1993 \vol 34 \issue 5 \pages 32--35 \mathnet{http://mi.mathnet.ru/pmtf3975} \transl \jour J. Appl. Mech. Tech. Phys. \yr 1993 \vol 34 \issue 5 \pages 625--628 \crossref{https://doi.org/10.1007/BF00859826}