Amu is the abbreviation of atomic mass unit, which was widely used to represent atomic mass unit before 196 1 year.
At that time, physics and chemistry had different definitions of amu. Physics thinks that amu is equal to the mass of oxygen116, and chemistry thinks that amu is equal to the average mass of oxygen116 (this involves the natural abundance of each isotope atom).
1960, IUPAP and 196 1 year, IUPAC recognized the unified atomic mass unit (u) as the unit to express atomic mass, and its value was equal to11. 1u =1.0003179amu (physical) = 1.000043amu (chemical). Now amu is generally only used in older literature.
In a word:1u =1am =1dalton.