Aradhna K. Tripati, Robert A. Eagle, Andrew Morton, Julian A. Dowdeswell, Katie L. Atkinson, Yannick Bahé, Caroline F. Dawber, Emma Khadun, Ruth M.H. Shaw, Oliver Shorttle, Lavaniya Thanabalasundaram,
Evidence for glaciation in the Northern Hemisphere back to 44 Ma from ice-rafted debris in the Greenland Sea Earth and Planetary Science Letters. ,vol. 265, pp. 112- 122 ,(2008) ,
10.1016/J.EPSL.2007.09.045