Reference books are often a good source of background information on topics related to entrepreneurship. They can help you to narrow your topic and will typically include bibliographies of additional resources.
Articles in the business press are likely to give you insights into financial issues, trends, major players and factors such as legislation or regulation that may affect small business management. Library databases can be used to find articles from newspapers, magazines and scholarly journals that cover business and management topics.
Websites that specialize in the study and promotion of entrepreneurship, such as Entrepreneurship.org, can be excellent sources of data and news, as well as a means to network with fellow entrepreneurs, although of course you must consider the possibility of bias in the way information is presented.
Some competitive intelligence may be called for! Do some research on the industry you're interested in, as well as companies that may be potential competitors (or suppliers/distributors, etc).
You'll need to do some market research to gauge expected demand for your proposed product or service. SLU Libraries provide access to several premium subscription sources for market research reports. Consumer demographics may also be useful.
Accounts of business success can provide great insights and inspirations for aspiring business leaders. Look for books by and about successful entrepreneurs like Bill Gates, Steve Jobs or Oprah Winfrey.
Entrepreneurship is an extremely broad and multi-disciplinary subject by its very nature. Depending on your specific research project, it may be appropriate to consult resources beyond those that are primarily business-focused, including psychology and communication resources. Please consult Judy Geczi, business librarian, for research assistance.