Preparative isolation of four ginsenosides from Korean red ginseng (steam-treated Panax ginseng CA Meyer), by high-speed counter-current chromatography coupled with evaporative light scattering detection - Ha, Y W; Lim, S S; Ha, I J; Na, Y C; Seo, J J; Shin, H; Son, S H; Kim, Y S (J Chromatogr A, 2007)