1. European Environment Agency 2018 https://www.eea.europa.eu/highlights/soil-contamination-widespread-in-europe
2. US Environment Agency 2017 https://www.epa.gov/enforcement/enforcement-annual-results-numbers-glance-fiscal-year-2017
3. Canadian Environment Assessment Agency 2017 https://www.canada.ca/en/environment-climate-change/services/federal-contaminated-sites/funding.html
4. US Environment Agency 2018 https://www.epa.gov/remedytech/remediation-technology-descriptions-cleaning-contaminated-sites
5. US Environment Agency 2018 https://www.unenvironment.org/explore-topics/disasters-conflicts/where-we-work/nigeria/environmental-assessment-ogoniland-report