Vi. Dragovich, INTEGRABLE PERTURBATIONS OF A BIRKHOFF BILLIARD INSIDE AN ELLIPSE, Journal of applied mathematics and mechanics, 62(1), 1998, pp. 159-162
Integrable perturbations which depend only on the coordinates of a Bir
khoff billiard inside an ellipse are considered. The class of integrab
le potentials which are polynomials in x y, x(-1) and y(-1) is describ
ed completely. (C) 1998 Elsevier Science Ltd. All rights reserved.