1. Mining costs are reported as All-In-Sustaining-Costs (AISC), a non-GAAP methodology introduced by the World Gold Council in 2013;the West Australian gold mining industry is 36,087 on-site employees (See: Western Australian Mineral and Petroleum Statistics Digest 2021-22),2022
2. This 19-year-old earns $54,000 a year mining bitcoin as a full-time job -here's what it's like" for more on how bitcoin miner employees work;For an interactive chart of bitcoin miner costs see
3. Cryptocurrency price volatility and investor attention;M Al Guindy;International Review of Economics & Finance,2021
4. Gold extraction from biosolid sludge obtained by sewage treatment;S Alketbi;Environmental technology,2019