Searching for eBooks is easy...
The majority of eBook files will be found by searching for
Documents.
Common file extensions are-
.pdf (Adobe Acrobat)
.lit (Microsoft Reader)
.tr (Tomeraider)
.txt
.rtf
.doc
.htm
.html
You may also wish to search
All because some people share multiple files in one compressed file (.rar or .zip). This is especially common with .htm or .html files where they are often individual chapters - the only way that they can be shared is in a compressed format.
The above comments also often apply to Audio eBooks.
Last for now... Many eBooks are available for free download from author or publisher websites.
p.s. This may be of interest >
Audiobook Podcast Collection - Download Free Audiobooks | Open Culture
or >
TomeRaider - TomeRaider 3 is the world's most advanced cross-platform reference viewer
Tomeraider files can be very easily copied and pasted into Word (for example) and with the Pro version of Adobe Acrobat Reader it is very simple to create .pdf files.