By A Mystery Man Writer
A personal trainer and the Tone It Up girls shared 16 exercises to help strengthen and tone your core.
Core Strength Benefits and Exercises to Improve Your Workout - The New York Times
Lower Ab Workout: 10 Exercises for a Stronger Core
7 Abs Exercises to Tighten Stomach Muscles for a Strong Core
Stretch, Bend and Kick by Tracy Anderson
How to Strengthen Your Core Muscles - CalorieBee
7 Abs Exercises to Tighten Stomach Muscles for a Strong Core
7 Abs Exercises to Tighten Stomach Muscles for a Strong Core
Lower Ab Workout: 10 Exercises for a Stronger Core
Tracy Anderson's 30-Day Core Challenge
Tracy Anderson's 15 Minute At-Home Workout
8 Unique Exercises for Better Abs and a Stronger Core - Muscle & Fitness
What is the best way to develop core strength? - Quora