1. “Porous silica particles containing a crystallized phase and method” Application No. US 3493341D A filed on 23-Jan-1967; Publication No. US 3493341 A published on 03-Feb-1970
2. “Process for producing silica in the form of hollow spheres” Application No. US 342525 A filed on 04-Feb-1964; Publication No. US 3383172 A published on 14-May-1968
3. F. Direnzo, H. Cambon, R. Dutarte, Microporous Mater. 10, 283–286 (1997)
4. M. Saadaoui, I. Fernández, A. Sánchez, P. Díez, S. Campuzano, N. Raouafi, J. Pingarrón, R. Villalonga, Electrochem. Commun. 58, 57–61 (2015)
5. B. Chang, D. Chen, Y. Wang, Y. Chen, Y. Jiao, X. Sha, W. Yang, Chem. Mater. 25, 574–585 (2013)