Primary Sources:
Andrew Jackson was US President at the time. Here is the transcript of the Speech he gave to Congress on the subject of 'Indian Removal' in 1830.
General Winfield Scott acted on behalf of the President to evict the Cherokee. Here is his speech to the Cherokee.
Negotiations with some of the Cherokee led to the signing of the Treaty of New Echota, the terms of which can be viewed here.
Principal Cherokee Chief John Ross strongly objected to the signing of the Treaty. He provided his perspective in a letter to Congress here.
Brief bio of John Ross for context.
Private John G Burnett was a soldier in the US Army who witnessed the suffering of the Cherokee. Here is his recollection.
The "500 Nations" documentary covers the topic really well and includes more quotes from the key players (here's a 5 minute clip):
Secondary Sources:
Richard White wrote about the Trail of Tears in a book called 'Native Americas: An Illustrated History'. Link to PDF
Two modern historians debate the question: "Was Andrew Jackson's Indian Removal Policy Motivated by Humanitarian Impulses?"