Roger Sawyer 
Slavery in the Twentieth Century [PDF ebook] 

Slavery in the Twentieth Century, first published in 1986, draws together all the forms of slavery in their modern guises — in the far recesses of Africa and Arabia, in the industrial towns of Italy, the factories and mines of South America, and in the prison farms of the United States. It shows that the definition of slavery is changing in the modern world, as it accommodates new forms of servitude and exploitation.