New Guaiane Sesquiterpene Lactones from Ixeris dentata - Cha, Mi-Ran; Choi, Yeon Hee; Choi, Chun Whan; Yoo, Dae Seok; Kim, Young Sup; Choi, Sang Un; Ryu, Shi Yong (Planta Medica, 2011)