Different cases of sequences of the Laplace Transformations for the 2D
Schrodinger operator in the periodic magnetic field and electric potential are
considered. They lead to the exactly solvable operators with nonstandard
spectral properties including the double-periodic operators with algebraic
Fermi surface known from the periodic soliton theory. Two appendices are added.
In the Appendix I (the author - S. Novikov) two discretizations of the 2D
operators and Laplace transformations are constructed. In the Appendix II (the
authors - S. Novikov and I. Taimanov) some nonstandard 1D discrete operators
are constructed with very interesting spectral properties.