The text suggests looking in your library for a further exploration of number theory and/or of Joseph Liouville. One might try doing the research on the Web. There are any number of "search engines" that will help you in your search. For example, one might try using the http://www.yahoo.com site. Once there, placing either Liouville or "number theory" in the Search box, and then clicking on the Search button should bring up a significant number of locations. On September 10, 2000, the former search produced a mere 6,270 items, while the latter produced 1 "Yahoo Category Match", 15 "Yahoo Site Matches", and about 57,200 "Web Page Matches". A search for "transcendental numbers" yielded 714 web page matches.