Little or no solar wind enters Venus' atmosphere at solar minimum - Zhang,TL; Delva,M; Baumjohann,W; Auster,H-U; Carr,C; Russell,CT; Barabash,S; Balikhin,M; Kudela,K; Berghofer,G; Biernat,HK; Lammer,H; et al. (NATURE, 2007)