APA
Drucker P. F., Collins J. C., . (2008). The five most important questions you will ever ask about your organization. [New York]: Leader to Leader Institute.
Chicago
Drucker Peter F, Collins James C, . 2008. The five most important questions you will ever ask about your organization. [New York]: Leader to Leader Institute.
Harvard
Drucker P. F., Collins J. C., . (2008). The five most important questions you will ever ask about your organization. [New York]: Leader to Leader Institute.
MLA
Drucker Peter F, Collins James C, . The five most important questions you will ever ask about your organization. [New York]: Leader to Leader Institute. 2008.