1. Alberti, G., Ottolini, M.: On the structure of continua with finite length and Gołab’s semicontinuity theorem. Nonlinear Anal. 153, 35–55 (2017)
2. Ambrosio, L., Fusco, N., Pallara, D.: Functions of bounded variation and free discontinuity problems. The Clarendon Press, Oxford University Press, New York, Oxford Mathematical Monographs (2000)
3. Oxford Lecture Series in Mathematics and Its Applications;L Ambrosio,2004
4. van den Berg, M., Buttazzo, G., Pratelli, A.: On the relations between principal eigenvalue and torsional rigidity. Commun. Contemp. Math. Preprint available http://cvgmt.sns.it. http://www.arxiv.org
5. Briani, L., Buttazzo G., Prinari, SF.: Some inequalities involving perimeter and torsional rigidity. Appl. Math. Optim. (2020) (to appear). http://cvgmt.sns.it. http://www.arxiv.org