The television mini-series Roots, first aired on ABC in 1977, is based on the 1976 historical novel Roots: The Saga of an American Family by Alex Haley. An instant bestseller, it was often assigned by teachers in the period as a vivid and appealing way to introduce students to the study of the slave trade and issues of race and civil rights. While Haley worked hard to strive for historical authenticity, Roots was not intended as a work of scholarship, and does not count as a scholarly source.
If you are doing research on the transatlantic slave trade, you should cite two types of sources: primary documents, actually written in the period, including slave narratives, newspaper articles, and abolitionist tracts, or secondary sources published in peer-reviewed scholarly journals. One useful starting point could be the extensive bibliography on the website of the International Slavery Museum (second reference below).