\bibitem{Burioni98}      R.~Burioni, D.~Cassi, A.~Pirati, S.~Regina,  \hskip 2mm 
                         {\it Diffusion on Nonexactly Decimable Tree-Like Fractals},
                         J.~Phys.~A: Math.~Gen. {\bf 31}, 5013-5019, 1998.