<unk>  is a standard way of calculating the due date for a pregnancy. It is named after Franz Karl<unk>  (1778-1851), the German obstetrician who devised the rule.
Naegele's rule
Behrens-Fisher problem
Gibbs' phase rule
Cassie's law
Hy's law
Hund's rule of maximum multiplicity
Kussmaul's sign
Weber–Fechner law