[{"Bold_text": "noun", "List Items": ["the standard unit of frequency in the International System of Units International System of Units(SI), equal to one cycle per second.:Hz"]}, {"Bold_text": "noun", "List Items": ["Gu·stav[goos, -tahf],1887–1975,German physicist: Nobel Prize 1925.", "Hein·rich Ru·dolph[hahyn, -, r, i, kh, , roo, -dawlf],1857–94,German physicist."]}]