SDT scholars are quite prolific and the body of research is ever growing (surprising amount of Canadian scholars actually) https://selfdeterminationtheory.org/research/
one of the creators of the theory is one of the most cited academics I know of https://www.semanticscholar.org/author/Richard-M.-Ryan/2242812951
Here's a short overview of the theory https://www.youtube.com/watch?v=wzN10--mNw8&t=175s