7Friis-ChristeMIen E, Lassen K. Length of the solar cycle: an indicator of solar activity closely associated with climate. Science, 1991, 254:698-700
8Eddy J A. The maunder minimum. Science, 1976, 192:1189-1202
9Eddy J A. Climate and the changing sun. Climate Change, 1977, 1:173-190
10Kodera K. Solar cycle modulation of the North Atlantic oscillation: implication in the spatiall structure of the NAO. Geophysical Research Letters, 2002, 29(8): 1029-1038