Ruben, Ruerd; Fort, Ricardo (2012). "The Impact of Fair Trade Certification for Coffee Farmers in Peru". World Development. 40 (3): 570–582. doi:10.1016/j.worlddev.2011.07.030. S2CID56357037.
Ruben, Ruerd; Fort, Ricardo (2012). "The Impact of Fair Trade Certification for Coffee Farmers in Peru". World Development. 40 (3): 570–582. doi:10.1016/j.worlddev.2011.07.030. S2CID56357037.