1. Ahokas , K 2015 Finland's phosphorus resources are more important than ever. Geofoorumi 2/2015 http://verkkolehti.geofoorumi.fi/en/2015/10/finlands-phosphorus-resources-are-more-important-than-ever/
2. British Broadcasting Corporation 2018 Russian spy: What are Novichok agents and what do they do? British Broadcasting Corporation, World News, 19 March https://www.bbc.com/news/world-europe-43377698
3. Portable, fully autonomous, ion chromatography system for on-site analysis;Elkin;J. Chromatogr.,2014
4. International Plant Nutrition Institute 2014 4R nutrient stewardship portal http://www.ipni.net/4R