A lemma on the minimal surfaces
  Stated lemma contains the assertions about isomorphism of exact m-forms and exterior differentials of regular m-maps, of linearly harmonic m-forms and exterior differentials of regular harmonic m-maps, of global minimal (n-m)-surfaces and level (n-m)-surfaces of regular minimal m-maps. It hold in n-dimensional Euclidean space. 
I.V. Bayak