Betty Azar is the founding author of Azar methodology and is the co-author of the Azar-Hagen Grammar Series. In her early career as an English teacher she started developing her own materials and worksheets to help her students grasp English grammar. Later on, she established her own approach to grammar teaching - Grammar Based Teaching (GBT) which became a foundation of the Azar-Hagen Grammar Series.
Stacy Hagen is the co-author of the Azar-Hagen Grammar Series. She's an experienced English Language teacher and administrator, as well as a published author of a number of ELT textbooks. She brings a wealth of rich new content, new exercise types, and a fresh, updated feel to the revisions.