Yet, while there are now many books and ideas about strategy formulation, there is very little research about how to link strategy with the nitty-gritty of sales execution.

FORBES: How to Break Through a Growth Stall

Net Minds keeps about 20 percent of book sales, and the author controls how to distribute his 80 percent share.

FORBES: Atari Founder Says His New Steve Jobs Book Will Be Published On A Novel Publishing Platform

Still, analysts have been concerned about how Apple could be affected by slowing sales of smart phones overall in the worsening economic environment.

WSJ: Apple to Give Glimpse of New iPhone Software

As a result, here's how to tell when the Apple craze is about to end: Watch how much profit it can wring out of every dollar of sales.

FORBES: Chief Executive Steve Jobs