Karlsson I, Antonsson L, Shi Y, Karlsson A, Albert J, Leitner T, Olde B, Owman C, Fenyö EM. HIV biological variability unveiled: frequent isolations and chimeric receptors reveal unprecedented variation of coreceptor use. AIDS. 2003 Dec 05;17(18):2561–9. doi: 10.1097/01.aids.0000096853.36052.36. PMID: 14685050.