By Luz Mestre-Oracle on Jul 30, 2014
The answer is very simple, please go the the link below and select the version you want to install.
It is a different story if you are adding one instance of your legacy systems, those versions are not available in the link above. You probably have the installer already.
However, if you don't have it, you can request the media as described in this My Oracle Support document:
Requesting Physical Shipment or Download URL for Software Media (Doc ID 1071023.1)
** you need to be logged to your My Oracle Support account to access the link.