MacTutor biography of Neumann

Variety (Universal Algebra) at Wikipedia

Preface to Varieties of Groups (1967), by Hanna Neumann

Biography (1974 obituary) of Hanna Neumann

Peter M. Neumann home page

Dynamic and algebraic compatibility of groups (1985 Dec. 11)

Groups related by a nontrivial identity (1985 Nov. 17)

Transformations over a bridge (1983 Aug. 16)

Group identity algebras (1983 Aug. 4)