Standardization of absolute CD4+ lymphocyte counts across laboratories: an evaluation of the Ortho CytoronAbsolute flow cytometry system on normal donors.
Connelly MC, Knight M, Giorgi JV, Kagan J, Landay AL, Parker JW, Page E, Spino C, Wilkening C, Mercolino TJ. Standardization of absolute CD4+ lymphocyte counts across laboratories: an evaluation of the Ortho CytoronAbsolute flow cytometry system on normal donors. Cytometry. 1995 Sep 15; 22(3):200-10.