1. Averis , A.B.G. Genney , D.R. Hodgetts , N.G. Rothero , G.P. Bainbridge , I.P. 2012 Bryological Assessment for Hydroelectric Schemes in the West Highlands 2nd edn Scottish Natural Heritage Commissioned Report 449b SNH, Inverness.
2. Business Dictionary 2014 Definitions of policy http://www.businessdictionary.com/definition/policy.html
3. CBD 2014 Invasive Alien Species http://www.cbd.int/invasive/background.shtml