The Informal Sector: Statistical Definition and Survey Methods,
by Ralf Hussmanns
• Collecting Informal Sector Statistics - the FIRST Methodology,
by Willem van den Andel
• Informal Sector Statistics: Experiences from Specialized Surveys,
by Margarita F. Guerrero
• A Minimum Data Set on the Informal Sector for National Accounting Purposes,
by Bernd Becker
• Progress in Measurement of the Informal Sector: Employment and Share of GDP,
by Jacques Charmes