Eric Lingman has provided links to a large collection of free Microsoft books on a variety of topics on his blog post (link below).
http://blogs.msdn.com/b/mssmallbiz/archive/2014/07/07/largest-collection-of-free-microsoft-ebooks-ever-including-windows-8-1-windows-8-windows-7-office-2013-office-365-office-2010-sharepoint-2013-dynamics-crm-powershell-exchange-server-lync-2013-system-center-azure-cloud-sql.aspx
Some of the books that I found interesting were on Azure Cloud Design Patterns, SharePoint, Office 365, etc.
http://blogs.msdn.com/b/mssmallbiz/archive/2014/07/07/largest-collection-of-free-microsoft-ebooks-ever-including-windows-8-1-windows-8-windows-7-office-2013-office-365-office-2010-sharepoint-2013-dynamics-crm-powershell-exchange-server-lync-2013-system-center-azure-cloud-sql.aspx
Some of the books that I found interesting were on Azure Cloud Design Patterns, SharePoint, Office 365, etc.
