<https://secure.gravatar.com/avatar/4e7d82ec2b109153c9bea7be6988383f?s=96&amp;d=mm&amp;r=g>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://sloanschoolofmusic.com/pitch-range-of-musical-instruments/>