“…Growth rates of groups, semigroups and group expansions. Wiegold's paper initiated a program of research into growth rates of groups including, for example, [5,6,7,8,9,10,11,22,23,26,27,31,33,34,35,37,38]. The program expanded to include the investigation of growth rates of semigroups, in [28,36], and later to include the investigation of growth rates of more general algebraic structures, in [14,30].…”