Althoff, Keri N., Kelly A. Gebo, Stephen J. Gange, Marina B. Klein, John T. Brooks, Robert S. Hogg, Ronald J. Bosch, Michael A. Horberg, Michael S. Saag, Mari M. Kitahata et al. "CD4 count at presentation for HIV care in the United States and Canada: are those over 50 years more likely to have a delayed presentation?" AIDS research and therapy 7 (2010): 45.