1. Hilbert's Tenth Problem;Matiyasevich,1993
2. The problem of solvability of equations in a free semigroup;Makanin;Math. Sb.,1977
3. Undecidability of the positive ∀∃3-theory of a free semi-group;Durnev;Sib. Mat. Zh.,1995
4. Equations in a free group;Makanin;Izv. Akad. Nauk SSR Ser. Math.,1983
5. Decidability of the universal and positive theories of a free group;Makanin;Izv. Akad. Nauk SSSR, Ser. Mat.,1984