www.pdfdrive.net (books are outdated little bit here)
http://mirknig.su/ (Russian website for books)
https://uloz.to/d8fpAg2rwEcYh/large-book-collection (Extensive collection)
Try them and make your day!
Other Method By Using Index Search
Basically use this in google
-inurl:htm -inurl:html intitle:"index of" +("/ebooks"|"/book") +(chm|pdf|zip) +"BookName"
Replace BookName with the title of the ebook, you’ll find FTP servers hosting said file, should get a hit in the first site or two.
**-inurl:htm -inurl:html intitle:“index of” +("/ebooks"|"/book") +(chm|pdf|zip) +" *Scary stories* "**
You get any format or file by changing ‘‘epub’’ to mobi, pdf, and all other extensions that available for book, See below, replace the * epub * with extension you need.
**-inurl:htm -inurl:html intitle:“index of” +("/ebooks"|"/book") +(chm|pdf|zip| *epub* ) +"Scary stories"**