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Review your results. You will find chapters in different books. Take note of both the book title and the chapter title. For example, there is an entire book about Copernicus called Copernicus: A Very Short Introduction. There are also books The History of Astronomy: A Very Short Introduction and The Scientific Revolution: A Very Short Introduction where Copernicus is mentioned. Click the chapter title most relevant to your research.
Read the chapter, but then review the table of contents of the book. This is located in the left menu. Click any other chapters that might be relevant to your research.