Fundamental Lemma of Calculus of Variations
If
with Continuous second Partial Derivatives, then 
on the Open Interval
.- Hankel Transform
- Hann Function
- Hanning Function
- Hanoi Graph
- Hanoi Towers
- Hansen-Bessel Formula
- Hansen Chain
- Hansen Number
- Hansen's Problem
- Happy Number
- Harada-Norton Group
- Harary Graph
- Hard Hexagon Entropy Constant
- Hard Square Entropy Constant
- Hardy-Littlewood Conjectures
- Hardy-Littlewood Constants
- Hardy-Littlewood k-Tuple Conjecture
- Hardy-Littlewood Tauberian Theorem
- Hardy-Ramanujan Number
- Hardy-Ramanujan Theorem
- Hardy's Inequality
- Hardy's Rule
- Harmonic Addition Theorem
- Harmonic Analysis
- Harmonic Brick