I get the audio books via Amazon's Audible.com . I have an account and a plan with Audible.com where I get a credit every month that can be used to purchase any Audio book. It costs a monthly fee that varies depending on the number of credits you want to receive each month. The audible app provides an interface for smartphone access and you can use a desktop or laptop for playing audiobooks via Amazon's website. I do not know if there are other sources for Jim's audiobooks. You can purchase individual books via Audible.com with no plan. In general the monthly fee is cheaper than purchasing individual books. The credits can accumulate if you do not use them up each month.
Hope this helps.