Thieme R, Schramel P, Mahr W
Geburtshilfe Frauenheilkd. 1980 Feb;40(2):185-7. doi: 10.1055/s-2008-1037216.
By means of NAA 14 trace elements yet unknown in the human amniotic fluid were studied. The results seem to support the hypothesis that Rb and Br are essential trace elements.