Press
Baltzer, Basel, pp. 63-82.
COMPUTERS & MATHEMATICS WITH APPLICATIONS, 26 (4)., pp. 43-55.
SERDICA, 19, pp. 121-133.
Baltzer, Basel, pp. 83-106.
INTERNATIONAL JOURNAL ON INFORMATION THEORIES AND APPLICATIONS, 1 (4)., pp. 3-12.
János Bolyai Mathematical Society, Budapest, pp. 91-105.
SERDICA, 19, pp. 134-144.
ACTA SCIENTIARUM MATHEMATICARUM, 57 (1-4)., pp. 627-638.
ACTA CYBERNETICA, 11 (1-2)., pp. 35-47.
INFORMATION PROCESSING LETTERS, 46 (4)., pp. 179-184.