The previous link pointed to Amazon S3 web space, as mentioned in:
https://github.com/vhf/free-programming-books/pull/909
that does not seem appropriate.

Add a link to the Mercury User's Guide (PDF)

See: http://www.visual-prolog.com/

by kenneth ward church

Added one book on CLP programming in Prolog

In a "Go" section

replaced í with i in the url and it still takes me to the same place
even though my browser can interpret í, url_checker cannot do it
yet.

Added link to "Introducing Microsoft SQL Server 2014". http://blogs.msdn.com/b/microsoft_press/archive/2014/04/02/free-ebook-introducing-microsoft-sql-server-2014.aspx

The ftp:// protocol is not recognized as a link.

Programming for the Game Boy Advance.

It is C + Assembly so I'm not sure where to put it.

Added free book on partial evaluation.

Added the latest Red Gate SQL book, as well as a link to the complete Red Gate "library".

Add link to the JAVA EE7 Tutorial in the PDF version.