Ellagitannins and Oligomeric Proanthocyanidins of Three Polygonaceous Plants oleh Yun-Qiu Li, Masako Kitaoka, Juri Takayoshi, Ya-Feng Wang, Yosuke Matsuo, Yoshinori Saito, Yong-Lin Huang, Dian-Peng Li, Gen-ichiro Nonaka, Zhi-Hong Jiang, Takashi Tanaka