On the additive group structure of nonstandard models of Z
The group structure of Hecke groups H $(lambda_q)$
Absolutely representing systems and convolution operators in the complex domain
Normal boundary value problems for differential equations of higher order
F. G. MAKSUDOV, Z. I. ISMAILOV
$T_2$-objects in categories of filter and local filter convergence spaces
Extensions of Caristi-Kirk's theorem