Introduction

  • Walter Ledermann, "Introduction to the Theory of Finite Groups", 1961. The author uses the word complex to mean a subset of a group, a term that appears to have fallen into disuse now. I use the term subset or set, and the context implies that there is a group operation that can be applied to its elements.

  • David S. Dummit, Richard M. Foote, "Abstract Algebra", 1991.