CHALOUPKA, Jiří, Christian BERNHARDT and
Dominik MUNZAR. Microscopic gauge-invariant theory of the c-axis infrared response of bilayer cuprate superconductors and the origin of the superconductivity-induced absorption bands.
Physical Review B. USA: The American Physical Society, 2009, vol. 79, No 18, p. 184513-184529. ISSN 1098-0121.