How to: Parse and read a large spreadsheet document (Open XML SDK)

https://msdn.microsoft.com/en-us/library/office/gg575571.aspx

Getting started with the Open XML SDK 2.5 for Office

https://msdn.microsoft.com/en-us/library/office/bb456488.aspx

Welcome to the Open XML SDK 2.5 for Office

https://msdn.microsoft.com/en-us/library/office/bb448854.aspx

Open XML SDK 2.5 for Microsoft Office (Download)

https://www.microsoft.com/en-us/download/details.aspx?id=30425