A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
I think the most detailed book that focuses on features within Office 2011 and Excel 2011 is the reference book I wrote with Geetesh Bajaj. It's available at your local library here:
Office 2011 for Mac all-in-one for dummies
Once you have the basics down you will find it necessary to search on very specific topics. You might want to know about formulas specific to scientific investigation. Or maybe formulas for some other specific purpose. You can search the library site I linked to above using more specific search parameters.
The best training I know of is professor Mike Girvin's ExcelIsFun YouTube site. He has thousands of videos grouped by topics and they are searchable.
As Bob said, you can find great detail by using a web search for a specific topic.