Betty S. Azar. 2014. Basic English Grammar. U.S.A. : Pearson Education. 514 p.730 b. 

         Clear, direct and comprehensive, the Azar-Hagen Grammar series uses a Grammar-Based Teaching approach that blends grammar methodology with communicative methods. Grammar is used as the starting point for the development of all language skills — speaking, listening, reading, and writing. The Azar-Hagen Grammar series describes how English works and uses grammar as a springboard for interactive, communicative practice opportunities