During his academic years he also worked as a demonstrator and then as an intern at the Institute of Mathematics of the KLTE and he became an aspirant of professorsTibor Szele and László Rédei in Modern algebra in 1951 and since his graduation.
In 1954 he was appointed to an assistant professor at the Institute of Mathematics, KLTE.
He took the candidate (C.Sc.) of Mathematics degree in 1954 and was awarded Doctor of Science (D.Sc.) degree in mathematics in 1957.[1]
From 1960 until 1968 he acted as head of the Department of Algebra and Number Theory, Institute of Mathematics but as an associate professor (docent, reader) just until 1963.
In his memory and honour they established the Andor Kertész County Memorial Competition in Mathematics in 1988.
His papers were issued in both national and international prestigious professional research scientific journals, and numerous scientific articles and books were published.
He presented his talks at several conferences and at the different science forums and he developed significant research and professional relationships in Western, Central and Eastern Europe.
He died on 3 April 1974 in Budapest due to chronic and serious illness.
His father, Lajos Kertész (1899–1974) was a teacher of music. His mother was Mária Nyíri. He had three siblings. Andor Kertész's wife was Ilona Tóth, teacher of history and geography. They had two children, a daughter, physician Gabriella Kertész and a son, linguist András Kertész.
Kertész, Andor: On the decomposibility of abelian p-groups into the direct sum of cyclic groups, Acta Mathematica Academiae Scientiarum Hungaricae 3, 121–126, 1952.
Kertész, Andor–Szele, Tibor: On the smallest distrance of two lines in 3-space, Publicationes Mathematicae 2, Debrecen, 308–309, 1952.
Kertész, Andor: On fully decomposible abelian torsion groups, Acta Mathematica Academiae Scientiarum Hungaricae 3, 225–232, 1952.
Kertész, Andor: Systems of equations over modules : To Professor Alexander Kurosh on hit 50th birthday. Acta scientiarum mathematicarum, (18) 3–4. pp. 207–234. (1957)[3]
Kertész, Andor: On independent sets of elements in algebra : To Professor L. Rédei on his 60th birthday. Acta scientiarum mathematicarum, (21) 3–4. pp. 260–269. (1960)
Kertész, Andor: On multimodules, Archiv der Mathematik 13, 267–274, 1962.
Kertész, Andor: A new proof of Litoff's theorem, Acta Mathematica Academiae Scientiarum Hungaricae 23, 1–3, 1972.
Huynh, Dinh Van, In memory of Professor Andor Kertész, in K Richter (ed.), Erinnerungen an Andor Kertész (1929–1974). Georg Cantor Heft, Sonderheft (Georg-Cantor-Vereinigung der Freunde und Förderer von Mathematik und Informatik an der Martin-Luther-Universität Halle-Wittenberg. E V, Halle/Saale, 2010), 35–36.