There are some walk-through kind of instruction on installing Ubuntu on Macbook Pro (as dual boot OS along with Mac OS X), such as Lifehacker's post. But they are either too old that I worry if the particular details are still currently applicable, or the source is not particularly reliable. Any pointer to a good, reliable, and current source on this? I intend to install Ubuntu as a dual boot OS on my Macbook Pro (mid 2011 model).
I think the following link will help you : https://help.ubuntu.com/community/MactelSupportTeam/AppleIntelInstallation#Detailed_How-To
Here they have explained it very clearly:
Hope this will help you.