1. The value of honey bees as pollinators of U.S. crops in 2000.;RA Morse;Bee Culture,2000
2. Economic valuation of the vulnerability of world agriculture confronted with pollinator decline.;N Gallai;Ecol Econ,2008
3. Importance of pollinators in changing landscapes for world crops.;AM Klein;Proc Roy Soc Lond B Biol Sci,2007
4. Status of pollinators in North America,2006
5. Insect pollination of crops;JB Free,1993