  Self-similar solutions of the equation that describes spreading of a liquid
layer due to intermolecular forces are found. It is supposed that, when the
thickness of the layer reaches some magnitude of the order of the molecular
size, it turns into a monomolecular layer, which can be liquid or gaseous. To
describe the spreading of a drop, the solutions of the equations that describe
evolution of liquid or gaseous monomolecular layers are matched with the
self-similar solutions with using relevant boundary conditions.
