See also: W. Hansen, C. Steinebach, V.T. Dolgopolov, A.V. Aristov, J.P. Kotthaus, M. Halland, A.A. Shashkin
PACS: 72.70.+m, 73.40.Hm, 73.50.Td, 05.50.+q, 73.20.Dx