Professor at harvard university, has published an influential research article titled "the five competitive forces that shape strategy."

The answer is Michael Eugene Porter.

He was still a young associate professor at Harvard Business School when he published this research and it was highly influential. Porter's Five Competitive Forces that Shape Strategy is a tool used to analyze competition of an industry. His research was published in 1979. 

Ibelieve appendix i maybe wrong

In financial aspects, a depression is a sustained, long haul downturn in monetary movement in one or more economies. it is a more extreme monetary downturn than a recession, which is a slowdown in financial action through the span of a typical business cycle. a depression is an irregular and extreme type of recession. so depression is always followed by recession but it is not correct to state that a depression always follow a recession.