Final answer:
The part of a book used for further information is the bibliography, which lists various sources along with their publication details, while an index helps locate information within the book itself.
Step-by-step explanation:
In the context of a book, the part used for providing further information on a topic is typically the bibliography. A bibliography is a list comprising of various sources such as books, academic journal articles, periodicals, websites, and multimedia texts that have been used in the research and writing of the book. This comprehensive list includes crucial details like author names, titles, publishers, and publication dates. On the other hand, an index is a systematic list arranged alphabetically to help readers find information within the book, and it does not include external sources for further reading.