http://books.google.pt/books?id=x-XUJgAS7XAC&printsec=frontcover&dq=cria%C3%A7%C3%A3o+de+caracois&hl=pt-PT&sa=X&ei=NItsT_6QEMb68QPI9JW_DQ&redir_esc=y#v=onepage&q=cria%C3%A7%C3%A3o%20de%20caracois&f=false
http://books.google.pt/books?id=6MzMkw71P4wC&pg=PA113&dq=cria%C3%A7%C3%A3o+caracois&hl=pt-PT&sa=X&ei=DoxsT4fvM8_B8QO_4NC_DQ&sqi=2&redir_esc=y#v=onepage&q&f=false