1. Plantum, Leading position, http://www.plantum.nl/, consulted website in November 2012.
2. LEI, Uitgangsmaterialen: Motor voor export en innovatie, Agricultural Economics Research Institute (LEI), The Hague, 2012, http://edepot.wur.nl/193975.
3. International Seed Federation, Seed Imports and Exports, http://www.worldseed.org/isf/seed_statistics.html, consulted website in November 2012.
4. N. Louwaars, Seeds of confusion: the impact of policies on seed systems, PhD Thesis, Wageningen University, Wageningen, 2007, http://edepot.wur.nl/121915.
5. Innovation and knowledge transfer in the Dutch horticultural system;Dons,2008