  Closed expression for the Green's function of the stationary two-dimensional
Schrodinger equation for an electron in group-VI dichalcogenides in the
presence of a magnetic field is obtained in terms of the Whittaker functions.
The resulting Green's function operator is a~$8 \times 8$ matrix consisting of
four block-diagonal~$2\times 2$ matrices, each of them characterized by
different values of valley index and electron spin. The obtained results are
used to calculate local density of states induced by a neutral delta-like
impurity in the presence of a magnetic field within the lowest Born
approximation. The spatial electron density experiences either the Friedel-like
oscillations or an exponential decay as a function of the distance from the
impurity.
