The primary purpose of Entrepreneurs' Search for Sources of Knowledge is to explore the search process for knowledge used by entrepreneurs and entrepreneurial firms in pursuit of new opportunities, new product innovation opportunities in particular. The second purpose of this monograph is to present empirical evidence about the sources of knowledge that entrepreneurs and entrepreneurial firms actually use (and actually do not use) in an effort to allow observed behaviour to inform future economics and management theory about the search for and use of knowledge sources. And, the third purpose of this monograph is to generate new and more complete empirical efforts to construct databases and to conduct analyses--empirical analyses and case studies--related not only to entrepreneur's and entrepreneurial firm's search for and use of sources of knowledge but also to measure the trends in the impacts of their use.