For citations:

Vedyushkina V.V., Kibkalo V.A., Pustovoitov S.E. Realization of focal singularities of integrable systems using billiard books with a Hooke potential field. Chebyshevskii Sbornik. 2021;22(5):44-57. (In Russ.) https://doi.org/10.22405/2226-8383-2021-22-5-44-57