An Essay on the Culture and Manufacture of Indigo: To Which Was Awarded the Prize of Eight Hundred Rupees by the Madras Government, 1860. E-book. Formato PDF John Shortt   -  Forgotten Books, 2017  - 

Indigo-yielding plants, may be classed under three genera, viz., l, Indigofera; 2, Isatis and 3, Nem'um.