Kjeld Beeks3 articles listing Kjeld Beeks in Nature, Nature Communications, Science, indexed by Paperzzz from Crossref and OSF.Laser Mössbauer spectroscopy of 229 Th in CaF 2 ScienceFrequency reproducibility of solid-state thorium-229 nuclear clocks NatureFine-structure constant sensitivity of the Th-229 nuclear clock transition Nature Communications