extraccion de mercancias

http://books.google.com.co/books?id=TCCijJ0ERY0C&pg=PA122&lpg=PA122&dq=extraccion+agrupada&source=bl&ots=LBKzOEniTV&sig=L9ferRhBQv2HytRgzyeHU2GcHxU&hl=es&ei=JJrpSvtsy5bwBv2E4IkP&sa=X&oi=book_result&ct=result&resnum=4&ved=0CBEQ6AEwAw#v=onepage&q=&f=false