PHYSICAL REVIEW B, vol. 91, no. 20, page. 205116 - 205116, 2015-05-18
JOURNAL OF PHYSICS-CONDENSED MATTER, vol. 16, no. 50, page. 9163 - 9168, 2004-12-22
PHYSICAL REVIEW B, vol. 60, no. 19, page. 13257 - 13260, 1999-11-15