"How to clean up crypto mining—and what's at stake if we don't". Fast Company. Retrieved 2022-01-22. ↑ (PDF) http://blockchain.cs.ucl.ac.uk/wp-content/uploads/2021/11/UCL_CBT_DPS_Q32021_updated-2.pdf. {{cite web}}: Missing or empty |title= (help) [bare URL PDF] ↑ "DLT Environmental Impact".