Grushko's theorem

A topological proof of Grushko's theorem on free products

John R. Stallings · Mathematische Zeitschrift · 1965 · 78 citations

Natural Sciences, Mathematics, Topology +2

Presentations of groupoids, with applications to groups

Paul Higgins · Mathematical Proceedings of the Cambridge Philosophical Society · 1964 · 53 citations

Natural Sciences, Mathematics, Algebra +14

On free products of groups

Daniel H. Wagner · Transactions of the American Mathematical Society · 1957 · 52 citations

Management, Marketing Management, Group Dynamics +3