The Hierarchy of Management Skills:

During the past thirty years there has been substantial growth in management development activity in corporations within the United States and, for that matter, throughout the world. Drucker has said that in the mid‐40s there were few if any corporations that were concerned with management development, but by mid‐1970 there were literally thousands. The reason for the growth in management development programmes appears to be the rapidity with which knowledge is changing. Thus, much of today's knowledge will be obsolete in just a few years.