YU, Li,
Dominik MUNZAR, A. V. BORIS, P. YORDANOV,
Jiří CHALOUPKA, Th. WOLF, C. T. LIN, B. KEIMER and C. BERNHARD. Evidence for Two Separate Energy Gaps in Underdoped High-Temperature Cuprate Superconductors from Broadband Infrared Ellipsometry.
Physical Review Letters. USA: The Americal Physical Society, 2008, vol. 100, No 17, p. 177004-177007. ISSN 0031-9007.