Cisco 800 Series Integrated Services Routers Software Configuration Guide - Configuring a VPN Using Easy VPN and an IPSec Tunnel [Cisco 800 Series Routers] - Cisco
Configuration Professional: Site-to-Site IPsec VPN Between Two IOS Routers Configuration Example - Cisco
Configure Site to Site IPSec VPN Tunnel in Cisco IOS Router
Cisco 800 Series Routers - Cisco
Cisco 800 Series Router – IT Tips for Systems and Network Administrators