'On Becoming Extraordinary - Decoding Hellman & Friedman and other Star Professional Service Firms' reveals the strategy of Hellman & Friedman and the world's best professional service firms. The book takes the reader deep inside the workings of the 'peak of the pyramid'. Pieter Klaas Jagersma, Ph.D., is a researcher, business professor, and advisor to professional service firms. He serves on the supervisory board of various global companies.