Herstein 1975, §2, p. 26 Herstein, Israel Nathan (), Topics in algebra (ed. 2nd), Lexington, Mass.: Xerox College Publishing, MR0356988.
Hall 1967, §1.1, p. 1: „The idea of a group is one which pervades the whole of mathematics both pure and applied.” [„Ideea de grup este una răspândită în întreaga matematică, atât pură cât și aplicată.”] Hall, G. G. (), Applied group theory, American Elsevier Publishing Co., Inc., New York, MR0219593, introducere elementară.
Lang 2002, Chapter VI (vezi în particular p. 273 pentru exemple concrete) Lang, Serge (), Algebra, Graduate Texts in Mathematics, 211, Berlin, New York, ISBN978-0-387-95385-4, MR1878556.
Wussing 2007 Wussing, Hans (), The Genesis of the Abstract Group Concept: A Contribution to the History of the Origin of Abstract Group Theory, New York: Dover Publications(d), ISBN978-0-486-45868-7.
Wussing 2007, §III.2 Wussing, Hans (), The Genesis of the Abstract Group Concept: A Contribution to the History of the Origin of Abstract Group Theory, New York: Dover Publications(d), ISBN978-0-486-45868-7.
Wussing 2007, §I.3.4 Wussing, Hans (), The Genesis of the Abstract Group Concept: A Contribution to the History of the Origin of Abstract Group Theory, New York: Dover Publications(d), ISBN978-0-486-45868-7.