http://books.google.com.br/books?id=b3GletLoxVUC&pg=PT6&dq=15+estudos+de+piano&hl=pt-BR&ei=98mRTpnsBYOUtwf275npBQ&sa=X&oi=book_result&ct=result&resnum=3&ved=0CEIQ6AEwAg#v=onepage&q&f=true