US oil prices turn negative as demand dries up - BBC News
World oil market chronology from 2003 - Wikipedia
5 years crude oil chart | Chartoasis.com
Historical Crude Oil Price (in nominal dollars per barrel) | Download Scientific Diagram
How high will oil prices go in 2022? – GIS Reports
Chart: Oil Price Surges to Highest since 2008 | Statista
Economics, fundamentals, technology, finance, speculation and geopolitics of crude oil prices: an econometric analysis and forecast based on data from 1990 to 2017 | SpringerLink