Vale, D. Picture grammar for children: Answer key. Topic-based grammar practice.
Citazione stile Chigago Style (17a edizione)Vale, David. Picture Grammar for Children: Answer Key. Topic-based Grammar Practice.
Citatione MLA (8a ed.)Vale, David. Picture Grammar for Children: Answer Key. Topic-based Grammar Practice.
Attenzione: Queste citazioni potrebbero non essere precise al 100%.