Thanks for your question.
First and foremost, design thinking is an application driven methodology. Books and courses are ok to get introduced to the concepts, but field application gives you immense experience that is very valid to you.
Having said that, I think that there are several books on design thinking which are easy to comprehend.
Some books and websites that may help you
3. And Suddenly the Inventor Appeared, by G. Altshuller
Thanks and have a nice day!