Programming Windows: Writing Windows 8 Apps With C# and XAML
http://www.wowebook.info/book/programming-windows-6th-edition/
Programming Windows 8 Apps with HTML, CSS, and JavaScript
http://blogs.msdn.com/b/microsoft_press/archive/2012/10/29/free-ebook-programming-windows-8-apps-with-html-css-and-javascript.aspx