YouTube – NIST 800-171 Control 3.5.3 Use multifactor authentication for access to privileged accounts

CMMC Level 2 Assessment Guide

State of Alabama – System Maintenance Policy

Citrix Blogs – Security best practices: Multi-factor authentication

NIST SP 800-53: IA-2 Identification and Authentication (Organization Users)

CyberSheath- How Multi-Factor Authentication Protects Your Business

SANS Whitepaper – Two-Factor Authentication (2FA) using OpenOTP

Duo Multi-Factor Authentication

RSA SecurID Access

Thales