Kant's Revolution
Kant (PhilosophyBasics.com)
http://www.philosophybasics.com/philosophers_kant.html
Stanford Encyclopedia of Philosophy: Kant’s Critique of Metaphysics
http://plato.stanford.edu/entries/kant-metaphysics/
Dan Robinson: How are synthetic a priori judgments possible? (Oxford podcasts)
https://podcasts.ox.ac.uk/how-are-priori-synthetic-judgements-possible
Kant & Categorical Imperatives: Crash Course Philosophy #35
PHILOSOPHY – The Good Life: Kant (Wireless Philosophy)