1. O. Stern, W. Gerlach, Z. Phys. 9, 349 (1922)
2. O. Stern, Z. Phys 39, 751 (1926)
3. R. Frisch, Z. Phys. 86, 42 (1933)
4. D. DeMille, J.M. Doyle, A.O. Sushkov, Science 357, 990 (2017)
5. M.S. Safronova, D. Budker, D. DeMille, D.F.J. Kimball, A. Derevianko, C.W. Clark, Rev. Mod. Phys. 90, 025008 (2018)