Swan, M., & Walter, C. How english works: A grammar practice book with answers.
Citazione stile Chigago Style (17a edizione)Swan, Michael, e Catherine Walter. How English Works: A Grammar Practice Book with Answers.
Citatione MLA (8a ed.)Swan, Michael, e Catherine Walter. How English Works: A Grammar Practice Book with Answers.
Attenzione: Queste citazioni potrebbero non essere precise al 100%.