In addition to publishing the body of knowledge (BOK) and core knowledge requirements (CKR), the HRCI gives you hints and tips on what material to study for the PHR/SPHR exams. They include must-reads by authors such as:
Warren Bennis: Bennis is a management theorist in the areas of leadership and behavior management. In general, he states that the traditional organization structure of top-down authority is less effective than democratic or collaborative leadership. Although he has authored several books, you should take a strong look at his work on Douglas McGregor, one of the fathers of humanistic behavior management in the field of industrial psychology. The principles of both of these authors are very likely to be in one form or another on the exams.
Charles Handy: Handy is best known for his work on organizational strategy, so SPHR candidates should accord special study time to studying his theories. In short, he discusses the need for businesses to function as a community, with rights and shared responsibilities.
Geert Hofstede: A well-respected social psychologist, Hofstede pioneered work in the field of organizational culture. He developed the idea of dimensions of culture, specifically that individuals are "group animals" responding to a moral code of conduct and values that must exist in an organizational community. Familiarize yourself with the concepts of power distance, individualism versus collectivism, masculinity versus femininity, long- versus short-term orientation, and indulgence versus restraint.
Henry Mintzberg: The author of several management books, Mintzberg talks quite a bit about balancing the power of economic structures, in which he includes organizations. For purposes of the exams, take a look at his model of 10 managerial roles.
Kenichi Ohmae: Ohmae may be best known for his role in illuminating the lean manufacturing principles in the West. Started by Toyota in Japan, lean is a quality management program with the goal of stripping out waste and engaging in just-in-time production. His work, however, is quite broad and focuses on both operations and strategy, making him a necessary read for both PHR and SPHR exam takers.
Michael Porter: If you've taken any management strategy classes, you probably have heard of Porter's five forces. His work proved to be part of the foundation of scanning the environment during the strategic planning process for factors influencing a company's success or failure. They include supplier power, buyer power, competitive rivalry, threat of substitution, and threat of new entry. Also, be familiar with his five generic strategies.
C.K. Prahalad: Prahalad makes for good company on this list of pioneers. Much of his work was focused on corporate strategy and the need for business to break through traditional competitive boundaries and invent new markets. A great example of this is his book titled The Fortune at the Bottom of the Pyramid, which discusses how organizations can compete and profit while eradicating poverty.
Edgar Schein: A prolific author, Schein's work in organizational culture, leadership, and management theory is quite broad. PHR candidates will benefit from his work on modern career pathing and leadership development. SPHR candidates should go deep in his works about organizational culture and its impact on outcomes.
Peter Senge: Organizational learning is the focus of Senge's work. He viewed organizations as one whole system with inter-related parts (departments) that are completely dependent upon organizational health. Called systems thinking, it's the fifth discipline of how organizations learn, integrating the other four that include personal mastery, mental models, shared vision, and team learning.
Dave Ulrich's Scorecards: You must spend time on business and HR scorecards, and Ulrich is the man to help you. As HR practitioners, it's your responsibility to develop measurements that help your company make data-driven decisions. His work talks about what must be measured and the tools you may use to do so.