Hybrid–SharePoint BCS Exchange

Hybrid for SharePoint Server
http://technet.microsoft.com/en-us/library/jj838715.aspx

Hybrid for Exchange 2019 Server
http://techgenix.com/configuring-exchange-2019-exchange-online-hybrid-mode/

SharePoint Hybrid BCS – PDF
http://www.microsoft.com/en-us/download/confirmation.aspx?id=35593

Business Connectivity Services

2013

http://technet.microsoft.com/en-us/library/ee661740.aspx

2010

Step by Step Guides
SharePoint Designer Walk Through
 http://ikarstein.wordpress.com/2011/02/23/walkthrough-create-a-simple-bcs-connection-with-sharepoint-designer-2010/

Visual Studio
http://sharepoint.microsoft.com/blog/Pages/BlogPost.aspx?pID=444

More from Technet
http://technet.microsoft.com/en-us/sharepoint/ee518675.aspx