Active Directory Security Best Practices
Because why wouldn't you?
Best Practice Guide for Securing Windows Server Active Directory Installations
Best Practice Guide for Securing Active Directory Installations and Day-to-Day Operations: Part 1
Best Practice Guide for Securing Active Directory Installations and Day-to-Day Operations: Part 2
Windows Server 2003 Deployment Kit: Designing and Deploying Directory and Security Services
Windows Server 2003 Security Guide
Windows Server 2008 Security Guide
Achieving Autonomy and Isolation with Forests, Domains, and Organizational Units
Active Directory Security Technical Implementation Guide (Non-Microsoft Guide)
https://iase.disa.mil/stigs/stig/active-directory-stig-v1r1.pdf