| (511a)-(511l) | Summaries of articles published in this issue. |
| 511-515 | On elongations of totally projective $p$-groups by $p^{\omega+n}$-projective $p$-groups. Fuchs, László; Irwin, J. M. |
| 516-528 | Generalizations of the classical Chebyshev polynomials to polynomials in two variables. Dunn, Ken B.; Lidl, Rudolf |
| 529-547 | Contextual grammars vs. context-free algebras. Novotný, Miroslav |
| 548-555 | Distributivity of intervals of torsion radicals. Jakubík, Ján |
| 556-581 | Simultaneous integrability of an almost complex and an almost tangent structure. Bureš, Jarolím; Vanžura, Jiří |
| 582-588 | Factorizations of matrices and functions of two variables. Neuman, František |
| 589-607 | A singular spectral identity and inequality involving the Dirichlet integral of an ordinary differential expression. Everitt, William Norrie; Wray, S. D. |
| 608-622 | Absolutely convergent expansions associated with a boundary-value problem with the eigenvalue parameter contained in one boundary condition. Wray, S. D. |
| 623-626 | Congruence extension from a semilattice to the freely generated distributive lattice. Fleischer, Isidore |
| 627-629 | A simple proof of the minimax-theorem. Kummer, Bernd |
| 630-632 | The least separative congruence on a weakly commutative semigroup. Nagy, Attila |
| 633-639 | Asymptotic equivalence of differential equations with Stepanoff-bounded functional perturbation. Boudourides, Moses A.; Georgiou, Dimitris |
| 640-647 | The category of Pawlak machines. Novotný, Jiří |
| 648-654 | Coelevation of a graph. Mikola, Milan |
| 655-666 | Around Bolzano's approach to real numbers. Kurepa, Djuro R. |
| 667-670 | Bolzano's infinitesimal numbers. Laugwitz, Detlef |