Sales Strategy
Here's a thread where I talked a bit about it. The fact that you learn from the perspective of the Customer Journey (instead of the Selling Process) flips selling on its head and makes you so much more in tuned to connecting with the customer and getting the sale.
I talked a bit about it the notions this other thread.
It can be tough to find courses and programs on these outside of an actual $80,000 MBA program, despite its importance and absolute relevance to sales.
But... There are a few online places you can learn it to a high quality level.
This next one is not strategy and is more systematic than books, but if you want a full legit academic program in sales, and are willing to devote about half a year, Queen's University from Smith School of Business has an excellent reputation. They have a full-out program on Enterprise sales for 5 months for $500. (Just a few hours / week). It's actually one of the few online university programs strictly devoted to sales (a Professional multi-course certificate program).
Hopefully this helps.