Buyer Guide: Choose Cisco ISR Featured Routers, ISR4000, ISR1000, and More – Router Switch Blog
Hardware Installation Guide for Cisco 4000 Series Integrated Services Routers - Overview of the Cisco 4000 Series ISRs [Cisco 4000 Series Integrated Services Routers] - Cisco
Hardware Installation Guide for Cisco 4000 Series Integrated Services Routers - Overview of the Cisco 4000 Series ISRs [Cisco 4000 Series Integrated Services Routers] - Cisco