There are some links used in the text. 1.https://www.suez.com/en/who-we-are/innovating-for-the-future/transforming-waste-into-secondary-raw-materials 2. https://www.sciencedirect.com/science/article/pii/S1110062118301375 3. https://www.skny.com/artists/hugo-mccloud/featured-works?view=slider#14