J. Martin-Ortega, R.C. Ferrier, I.J. Gordon, and S. Khan, 2015, Water ecosystem services : a global perspective, UNESCO and Cambridge University Press, ISBN Cambridge 978-1-107-10037-4; ISBN UNESCO 978-92-3-100068-3, http://www.cambridge.org/bg/academic/subjects/earth-and-environmental-science/hydrology-hydrogeology-and-water-resources/water-ecosystem-services-global-perspective, Type of document: BookUNESCO and Cambridge University Press, UK, ISBN Cambridge 978-1-107-10037-4; ISBN UNESCO 978-92-3-100068-3, http://www.cambridge.org/bg/academic/subjects/earth-and-environmental-science/hydrology-hydrogeology-and-water-resources/water-ecosystem-services-global-perspective