An axiomatization of the propositional calculus and the completeness theorem J. D. Kečkić — 1968 Matematički Vesnik
On Some Classes Of Linear Equations III J. D. Kečkić; M. S. Stanković — 1982 Publications de l'Institut Mathématique
Generalisations of some inequalities of P. M. Vasić J. D. Kečkić; I. B. Lacković — 1970 Matematički Vesnik
Some properties of arithmetic means of real sequences P. M. Vasić; J. D. Kečkić; I. B. Lacković; Ž. M. Mitrović — 1972 Matematički Vesnik