Peter Drucker's book helps managers in big corporations and solo entrepreneurs to become more effective. A must read.

Peter Drucker (1909–2005) was a writer, management consultant, and self-described “social ecologist.” Widely considered to be the father of “modern management,” his 39 books and countless scholarly and popular articles explored how humans are organized across all sectors of society — in business, government and the nonprofit world. His writings have predicted many of the major developments of the late twentieth century, including privatization and decentralization; the rise of Japan to economic world power; the decisive importance of marketing; and the emergence of the information society with its necessity of lifelong learning. In 1959, Drucker coined the term “knowledge worker.”