(Inggris)"Primitive hematopoietic cells resist HIV-1 infection via p21Waf1/Cip1/Sdi1". Center for Regenerative Medicine, Massachusetts General Hospital, Division of Infectious Diseases, Beth Israel Deaconess Medical Center, Harvard Medical School, Harvard Stem Cell Institute; Jielin Zhang, David T. Scadden dan Clyde S. Crumpacker. Diakses tanggal 2010-12-12.
(Inggris)"Lipid Synthetic Transcription Factor SREBP-1a Activates p21WAF1/CIP1, a Universal Cyclin-Dependent Kinase Inhibitor". Department of Internal Medicine, Institute of Clinical Medicine, Center for Tsukuba Advanced Research Alliance, University of Tsukuba, Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, University of Tokyo; Noriyuki Inoue, Hitoshi Shimano, Masanori Nakakuki, Takashi Matsuzaka, Yoshimi Nakagawa, Takashi Yamamoto, Ryuichiro Sato, Akimitsu Takahashi, Hirohito Sone, Naoya Yahagi, Hiroaki Suzuki, Hideo Toyoshima, dan Nobuhiro Yamada. Diakses tanggal 2010-12-12.