  A multidimensional cosmological model with space-time consisting of n (n>1)
Einstein spaces M_i is investigated in the presence of a cosmological constant
Lambda and m homogeneous minimally coupled scalar fields as a matter source.
Classes of the models integrable at classical as well as quantum levels are
found. These classes are equivalent to each other. Quantum wormhole solutions
are obtained for them and the procedure of the third quantization is performed.
An inflationary universe arising from classically forbidden Euclidean region is
investigated for a model with a cosmological constant.
