Hook, E. B., Topol, B. B., & Cross, P. K. (1989). The natural history of cytogenetically abnormal fetuses detected at midtrimester amniocentesis which are not terminated electively: New data and estimates of the excess and relative risk of late fetal death associated with 47,+21 and some other abnormal karyotypes.

Hook, E B., B B. Topol, ja P K. Cross. The Natural History of Cytogenetically Abnormal Fetuses Detected At Midtrimester Amniocentesis Which Are Not Terminated Electively: New Data and Estimates of the Excess and Relative Risk of Late Fetal Death Associated With 47,+21 and Some Other Abnormal Karyotypes. 1989.

Hook, E B., B B. Topol, ja P K. Cross. The Natural History of Cytogenetically Abnormal Fetuses Detected At Midtrimester Amniocentesis Which Are Not Terminated Electively: New Data and Estimates of the Excess and Relative Risk of Late Fetal Death Associated With 47,+21 and Some Other Abnormal Karyotypes. 1989.