Yan Zhong, X., Holzgreve, W. and Hahn, S. (2001) “Risk-free simultaneous prenatal identification of fetal Rhesus D status and sex by multiplex real-time PCR using cell free fetal DNA in maternal plasma”, Swiss Medical Weekly, 131(0506), pp. 70–74. doi: 10.4414/smw.2001.09660.