In regards to grey literature, nowadays most of the data is available in the network for online consultation.

The main centers of data provision are

• Instituto Galego de Estatística
• Instituto Nacional de Estadística
• Eurostat
• United Nations
• UNESCO
• International Organization for Migration (IOM)
• World Tourism Organization (UNWTO)
• World Health Organization (WHO)
• World Bank
• International Monetary Fund (IMF)
• The Organization for Economic Co-Operation and Development (OECD)
• International Labour Organization (ILO)
• Amnistía Internacional (NGO)