Editorial: Adding Value, by Michael Hailu, ‘’Spore’’ No 157 Andreas Stamm and Christian von Drachenfels “Value Chain Development: Approaches and activities by seven UN agencies and opportunities for interagency cooperation” ILO Webber, C. M.; P. Labaste.
Truy cập ngày 24 tháng 2 năm 2014.  ^ Editorial: Adding Value, by Michael Hailu, ‘’Spore’’ No 157 ^ Andreas Stamm and Christian von Drachenfels “Value Chain Development: Approaches and activities by seven UN agencies and opportunities for interagency cooperation” ILO ^ Webber, C. M.; P. Labaste.