Hantzsch–Widman name, 655 hapten, 656 hapto, 656 hard acid, 656 hard amorphous carbon films, 656 hard base, 656 hard-segment phase domain, 657hard-sphere collision cross section, 657 harmonic approximation, 657 harmonic frequency generation, 657 harmonic mean, 658 harpoon mechanism, 658 hartree, 658