Here are some good articles and reports for further reading:

Norway Provides $10 Million to Support World Bank on Reforming Tax Systems in Fragile States September 12, 2019

World Bank: Mobilizing Tax Resources to Boost Growth and Prosperity in Sub-Saharan Africa September 9, 2019

World Economic Forum: 3 ways to get Africa's informal economy on the books August 29, 2019

UNECA: Africa could earn $ 99 billion a year by improving its tax revenues (in french). March 25, 2019.

Tax reform, digitization key to financing Africa’s development – UNECA report. March 23, 2019.

McKinsey podcast. How to win Africa. November 2018

Afrique Le Point: Secteur informel : le numérique au secours des recettes des États? June 9, 2018.

More than 61 per cent of the world’s employed population – two billion people – earn their livelihoods in the informal sector, the United Nations labour agency said, stressing that a transition to the formal economy is critical to ensure rights’ protection and decent working conditions. Women and men in the informal economy: A statistical picture 2018

Le Point Afrique "Afrique : le secteur informel fait sa révolution". Viviane Forson. July 18, 2017.

IMF Working Papers: The Informal Economy in Sub-Saharan Africa : Size and Determinants. Leandro Medina, Andrew W Jonelis, Mehmet Cangul. July 10, 2017

The Power of the Poor - Full Video (YouTube). Dec 30, 2015.

Informal Sector In Francophone Africa: Firm Size, Productivity, And Institutions (PDF), 2012 • N. Benjamin, A. A. Mbaye, I. A. T. Diop, Stephen S. Golub, D. Haughton. 2012The free market secret of the Arab revolutions, Financial TImes, Hernando de Soto, November 8,  2011

The Informal Economy: Fact Finding Study (PDF). Department for Infrastructure and Economic Cooperation. March 2004 • Kristina Flodman Becker. March 2004

The Informal sector, Wikipedia

The Arab Spring, Wikipedia