1. A. N. Ryaskin, “The number of models of complete theories of unars,” in:Model Theory and Its Applications, Tr. Inst. Mat. SO AN SSSR,8 (1988), pp. 162–182.
2. C. Toffalori, “1-Ary functions and the f.c.p.,”Illinois J. Math.,35, No. 3, 434–450 (1991).
3. H. J. Keisler, “Ultraproducts which are not saturated,”J. Symb. Logic,32, No. 1, 23–46 (1967).
4. L. Marcus, “The number of countable models of a theory of one unary function,”Fund. Math.,108, No. 3, 171–181 (1980).
5. S. Shelah,Classification Theory and the Number of Non-Isomorphic Models, North-Holland, Amsterdam (1978).