<https://kienedu.com/san-pham/skkn-giup-hoc-sinh-lop-4-xac-dinh-tot-phan-tu-loai>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://kienedu.com/san-pham/skkn-giup-hoc-sinh-lop-4-xac-dinh-tot-phan-tu-loai>