1. Agro atlas: Interactive Agricultural Ecological Atlas of Russia and Neighboring Countries 2009 Economic Plants and their Diseases , Pests and Weeds . http://www. agroatlas.ru /en/content/weeds/Lappula_squarrosa/ December
2. Bundes institut für Risikobewertung (BfR) [Federal Institute of Risk Assessment] 2011 Chemical Analysis and Toxicity of Pyrrolizidine Alkaloids and Assessment of the Health Risks Posed by their Occurrence in Honey , BfR Opinion No. 038/2011. BfR: Berlin http://www.bfr.bund.de/cm/343/analytik-und-toxizitaet-von-pyrrolizidinalkaloiden.pdf August
3. Commission Decision 2008 Authorizing the Placing on the Market of Refined Echium Oil as Novel Food Ingredient , Commission Directive No. 258/97/EC. European Parliament and of the Council: Brussels November
4. Committee on Toxicity (COT) 2008 COT Statement on Pyrrolizidine Alkaloids in Food. Committee on Toxicity of Chemicals in Food , Consumer Products and the Environment , Statement on Pyrrolizidine . COT: London http://cot.food.gov.uk/sites/default/files/cot/cotstatementpa200806.pdf September