To find books on entrepreneurship, try searching the library catalogue for the following subject headings:
Notice all of the sub-headings beneath the major subject terms, which allow you to get more and more specific in terms of topic or geographic location.
The same terms (and more) will work as keyword search terms - but a subject search will retrieve more precise results.
You can also do an 'advanced keyword search' and restrict the 'material type' to limit your search to e-books only.