MOROSHKIN, P.; HOFER, A.; ULZEGA, S.; WEIS, A. Spectroscopy of atomic and molecular defects in solid ⁴He using optical, microwave, radio frequency, magnetic and electric fields (Review Article). ФІЗИКА НИЗЬКИХ ТЕМПЕРАТУР, Харків, Україна, v. 32, n. 11, p. 1297–1319, 2006. DOI: 10.1063/1.2389001. Disponível em: https://fnt.ilt.kharkov.ua/index.php/fnt/article/view/f32-1297e. Acesso em: 24 лис. 2024.