<https://www.owlgen.in/explain-the-law-of-demand-and-why-does-the-law-of-demand-operate/#article>
<http://www.w3.org/1999/02/22-rdf-syntax-ns#type>
<https://www.owlgen.in/explain-the-law-of-demand-and-why-does-the-law-of-demand-operate/>