V. H. Grigoryan, A. Y. Stepanyan, A. N. Arakelyan, and H. R. Aghababyan, “THE INVESTIGATION OF HEART RHYTHM VARIABILITY DURING FULFILMENT OF MAZE-MODEL TASKS”, Proc. YSU B: Chem. Biol. Sci., vol. 38, no. 1 (203), pp. 105–110, Dec. 2003.