- harmonic operator
- harmonic pencil of lines
- harmonic pencil of planes
- harmonic p-forms
- harmonic polynomial
- harmonic polynomial
- harmonic progression
- harmonic property of a complete quadrangle
- harmonic property of a complete quadrilateral
- harmonic quadrilateral
- harmonic range of points
- harmonic ratio
- harmonic series
- harmonic series
- harmonic sheaf
- harmonic sheaf associated with a hyperharmonic sheaf
- harmonic space
- harmonious graph
- harmonious labeling
- Harnack convergence theorem
- Harnack inequality
- Harnack inequality
- Harnack inequality for weak solution
- Harnack lemma
- Harnack principle