Kravets, V G; Jalil, R; Kim, Y-J; Ansell, D; Aznakayeva, D E; Thackray, B; Britnell, L; Belle, B D; Withers, F; Radko, I P; Han, Z; Bozhevolnyi, S I; Novoselov, K S; Geim, A K; Grigorenko, A N