Back to History of Ultrasound in Obstetrics and Gynecology. 
The paper from D Hofmann and Hans Hollander in 1968 on the prenatal diagnosis of Hydrops fetalis using ultrasound (the Vidoson). The paper covered 3 pages in which they reported 9 cases of Hydrops fetalis. There were 4 ultrasound images of hydropic fetuses made with the Vidoson.