Directories are a great resource for browsing for authoritative organizations that might collect the information you need.
Indicators are specific measurements that offer clues as to whether a phenomenon is present or absent. This list is of commonly used indicators, but there are many more than this that may be useful to you depending on your research question.
Industrialization, Economic Policy and Debt dataset
Urbanization, Environment dataset
Education, Education dataset
Inequality, Poverty dataset
Wealth from extractive industries, Environment dataset
Foreign aid, Economic Policy and Debt dataset
This tutorial walks you through finding economic indicators from the World Bank in Sage Data (formerly known as Data Planet).