Perspectives on the quality assurance of ginseng products in North America - Fitzloff, J; Yat, P; Lu, Z; Awang, D VC; Arnason, J T; van Breemen, R B; Hall, T; Blumenthal, M; Fong, H HS (Advances in Ginseng Research – Proceedings of the 7th International Symposium on Ginseng, 1998)