Referencias interesantes sobre Excel Services
Excel Services Technical Overview
https://msdn.microsoft.com/en-us/library/aa972194.aspx
The basics of using Kerberos in a Sharepoint environment.
https://www.windowsecurity.com/articles/Kerberos-Sharepoint-Environment.html
Algunos tutoriales de uso de Excel Services
Setting up the Server - Step 1: Creating a Trusted Location with Excel Services
Setting up the Server - Step 2: Configuring Single Sign-On for Excel Services
Setting up the Server - Step 3: Creating a Trusted Data Connection Library with Excel Services
Building a Report Based on Cube Functions for Excel Web Access
Protecting Workbook Intellectual Property (IP) with View Item Rights
Using OLAP Formulas, Conditional Formatting, and Charts
Building an OLAP PivotTable Report with Excel Services
Building a Relational PivotTable Report with Excel Services
Building a Report with a Chart for Excel Web Access Based on Cube Functions
Creating a Multi-Report Summary Page of Reseller Sales Data
How to configure SharePoint Server 2007 and Excel Services for Kerberos authentication
https://support.microsoft.com/kb/953130/en-us
Configuring Kerberos for SharePoint 2007: Part 1 - Base Configuration for SharePoint
Configuring Kerberos for SharePoint 2007: Part 2 - Excel Services and SQL Analysis Services