• Cha, Sangmi, and Heekyong Yang. “Urea Shortage Threatens South Korea’s Transport, Energy Industries”. Reuters, 9 Nov. 2021. www.reuters.com, https://www.reuters.com/business/energy/urea-shortage-threatens-south-koreas-transport-energy-industries-2021-11-09/.
• Hannam, Peter. “What Is Urea and AdBlue, and Why Does a Worldwide Shortage Threaten Australia’s Supply Chain?”. The Guardian, 10 Dec. 2021. The Guardian, https://www.theguardian.com/australia-news/2021/dec/08/what-is-urea-and-why-does-a-worldwide-shortage-threaten-australias-supply-chain.
• King, Ryan Erik. “Global Urea Shortage Could Park Diesel Trucks”. Jalopnik, 12 Dec. 2021, https://jalopnik.com/global-urea-shortage-could-park-diesel-trucks-1848201479.
• Zhong, Raymond. “This Chemical Is in Short Supply, and the Whole World Feels It”. The New York Times, 6 Dec. 2021. NYTimes.com, https://www.nytimes.com/2021/12/06/business/urea-fertilizer-food-prices.html.