Your Core Muscles - Deeper Than You Think - Yoga Anatomy
The Common Core Explained
What Are Core Muscles? The Role of Each Core Muscle and Best Exercises
Core
Strange twist: Earth's inner core may be changing its spin direction
Earth's inner core may have a whole other core inside it
Explained: Dynamo theory, MIT News
What are the Core Muscles?
A Closer Look at Mercury's Spin and Gravity Reveals the Planet's Inner Solid Core - NASA