Sharing for information only.

Introducing Windows 8: An Overview for IT Professionals (Final Edition)
http://blogs.msdn.com/b/microsoft_press/archive/2012/11/13/free-ebook-introducing-windows-8-an-overview-for-it-professionals-final-edition.aspx

Introducing Microsoft SQL Server 2012
http://blogs.msdn.com/b/microsoft_press/archive/2012/03/15/free-ebook-introducing-microsoft-sql-server-2012.aspx

Introducing Windows Server 2012 (RTM Edition)
http://blogs.msdn.com/b/microsoft_press/archive/2012/09/05/free-ebook-introducing-windows-server-2012-rtm-edition.aspx

Microsoft Lync Server 2013 Step By Step for Anyone eBook (pdf) English
http://gallery.technet.microsoft.com/office/Lync-Server-2012-9d6fe954

Deployment guide for Office 2013
http://social.technet.microsoft.com/wiki/contents/articles/11608.e-book-gallery-for-microsoft-technologies.aspx#Office2013Deploy

Explore SharePoint 2013
http://social.technet.microsoft.com/wiki/contents/articles/11608.e-book-gallery-for-microsoft-technologies.aspx#SP2013Explore

Deployment Guide for SharePoint 2013
http://social.technet.microsoft.com/wiki/contents/articles/11608.e-book-gallery-for-microsoft-technologies.aspx#SP2013Explore

Microsoft Office 365: Connect and Collaborate Virtually Anywhere, Anytime
http://social.technet.microsoft.com/wiki/contents/articles/11608.e-book-gallery-for-microsoft-technologies.aspx#Office2013Deploy