* Y. Kozai "Secular perturbations of asteroids and comets" In: Dynamics of the solar system; Proceedings of the Symposium, Tokyo, Japan, May 23–26, 1978.
* Y. Kozai "Secular perturbations of asteroids and comets" In: Dynamics of the solar system; Proceedings of the Symposium, Tokyo, Japan, May 23-26, 1978.