Sohnesen, T. P., & Blom, A. (2005). Is formal lifelong learning a profitable investment for all of life?: How age, education level and flexibility of provision affect rates of return to adult education in Colombia. World Bank.

Sohnesen, Thomas Pave, and Andreas Blom. Is Formal Lifelong Learning a Profitable Investment for All of Life?: How Age, Education Level and Flexibility of Provision Affect Rates of Return to Adult Education in Colombia. Washington, D.C: World Bank, 2005.

Sohnesen, Thomas Pave, and Andreas Blom. Is Formal Lifelong Learning a Profitable Investment for All of Life?: How Age, Education Level and Flexibility of Provision Affect Rates of Return to Adult Education in Colombia. World Bank, 2005.