Start with the Cambridge Advanced 4 for pressure-testing. Move to Hewings for fine grammar. Finish with Longman Academic Writing for production. These books are rare, demanding, and expensive... but they are the only gear that will get you to the summit of fluency.
It deals with serious themes—racism, survival, and identity—using a mix of humor and sophisticated storytelling. c1 english level books exclusive
by F. Scott Fitzgerald : A masterclass in 1920s American prose. It is short but densely packed with vivid imagery and complex sentence structures. The Picture of Dorian Gray Start with the Cambridge Advanced 4 for pressure-testing