Herstein 1975, §2, pp. 26 Hall 1967, §1.1, pp. 1: "The idea of a group is one which pervades the whole of mathematics both pure and applied."
Herstein 1975, §2, pp.  26 Hall 1967, §1.1, pp.  1:“群的想法遍布在包括純數學和應用數學二者的整個數學中。