I have reactivated this offer. It still works as described. Use the promotion code during the purchase to receive the discount.
Go to The Great Courses and use this promotional code to save 20% off your order of $100 or more. Just go and apply this coupon code in your shopping bag at checkout.
I am re-activating this expired deal. I will update it and validate that it works. Get 20% Off Your Order $100 or More at The Great Courses (Site-wide).