Four New 6-Nor-5(6→7)abeo-abietane Type Diterpenes and Antitumoral Cytotoxic Diterpene Constituents from the Bark of Taiwania cryptomerioides - Chang, Chi-I; Chang, Jang-Yang; Kuo, Ching-Chuan; Pan, Wen-Yu; Kuo, Yueh-Hsiung (Planta Medica, 2005)