T. Banakh and N. Lyaskovska, Weakly P-small not P-small subsets in groups, Intern. J. Algebra Computations, 18 (2008), 1-6. http://dx.doi.org/10.1142/S0218196708004263
M. Filali and I. Protasov, Ultrafilters and Topologies on Groups, Math. Stud. Monorg. Ser., Vol. 13, VNTL Publishers, Lviv, 2010.
V. Gavrylkiv, Algebraic-topological structure on superextensions, Dissertation, Lviv, 2009.
The Kourovka Notebook, Novosibirsk, Institute of Math., 1995.
K. Kuratowski, Topology, Vol. 1, Academic Press, New York and London, PWN, Warszawa, 1969.
Ie. Lutsenko, Thin systems of generators of groups, Algebra and Discrete Math., 9 (2010), 108-114.
Ie. Lutsenko and I. V. Protasov, Sparse, thin and other subsets of groups, Intern. J. Algebra Computation, 19 (2009), 491-510. http://dx.doi.org/10.1142/S0218196709005135
I. V. Protasov, Selective survey on Subset Combinatorics of Groups, J. Math. Sciences, 174 (2011), 486-514. http://dx.doi.org/10.1007/s10958-011-0314-x
I. Protasov and T. Banakh, Ball Structure and Colorings of Groups and Graphs, Math. Stud. Monorg. Ser., Vol. 11, VNTL Publishers, Lviv, 2003.
T. Tao and V. Vu, Additive Combinatorics, Cambridge University Press, 2006. http://dx.doi.org/10.1017/CBO9780511755149