<https://academy.allaboutbirds.org/discussion/topic/what-makes-a-hummingbird-a-hummingbird/#schema-webpage>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://academy.allaboutbirds.org/discussion/topic/what-makes-a-hummingbird-a-hummingbird/page/6>