2012 Macbook Pro 13" A1278 DVD Super Drive Replacement - YouTube
Upgrade Your Macbook Pro (SSD Upgrade, RAM Upgrade, Optical Drive Bay Adapter) - YouTube
How-To: Now's the right time to swap your old iMac's hard drive for a fast new SSD - 9to5Mac
Hard Drive Caddy Tray 2nd HDD SSD Kit Compatible with 2.5" 9.5mm SATA HDD SSD 2nd HDD Adapter for Apple MacBook Pro Unibody 13 15 17 SuperDrive DVD Drive : Amazon.co.uk: Computers
How to install an SSD on a 15-inch Retina MacBook Pro
Advice from an Apple Tech: How to replace the optical drive in a Unibody MacBook Pro with a second hard drive | Macworld
Install an SSD into the optical superdrive slot on a MacBook Pro | OSXDaily
HDD Caddy for Macbook Pro 13, 15, 17 inch Unibody
Amazon.com: Padarsey 2nd HDD SSD Hard Drive Caddy Tray Replacement for MacBook Pro 13/15/17 inch A1278 A1286 A1297 2008 2009 2010 2011 2012 Internal Laptop CD/DVD-ROM Optical SuperDrive Adapter to 2.5 Inch 9.5MM : Electronics
Advice from an Apple Tech: How to replace the optical drive in a Unibody MacBook Pro with a second hard drive | Macworld
SSD adapter kit: replace Apple SuperDrive with hard disk
Installing MacBook Pro 15" Unibody Mid 2012 Dual Hard Drive - iFixit Repair Guide