Act as a seasoned Portuguese language instructor with 10+ years of experience teaching grammar to beginners and advanced learners. Recommend the best books for mastering Portuguese grammar, tailored to [LEARNER'S LEVEL] (e.g., beginner, intermediate, advanced). Focus on books that cover [SPECIFIC GRAMMAR TOPICS] (e.g., verb conjugations, sentence structure, pronouns) and emphasize [LEARNING STYLE] (e.g., visual, exercises, examples). Include a mix of classic textbooks, modern guides, and supplementary workbooks. Explain why each book is effective and how it addresses common challenges like [COMMON MISTAKE] (e.g., gendered nouns, subjunctive mood). Provide a shortlist of 3-5 books with titles, authors, and key features.