I am looking for research and papers on the impact of informal/unregulated suppliers on market prices and negative externalities. I am particularly interested in the manufacturing sector.
A quick way to do this would be through google scholar? Papers are then available via libgen or scilib
If you're part of an institution such as a university then you should have access to EBSCO Econlit which allows you to scan every economics paper using Boolean search strings to filter down to what you're looking for.