Published online by Cambridge University Press: 14 August 2015
In 1962 the author published a paper on secular perturbations of asteroids with high eccentricity and inclination (Kozai, 1962) and found that for such asteroids the secular perturbations are more complicated than those estimated by the classical linear theory. Before that the author(Kozai, 1954) tried to extend the classical theory to include terms of squares of disturbing masses, eccentricities and inclinations in expressions of secular motions of angular variables and found that the sum of the longitudes of the perihelion and the ascending node is not as stable quantity as the classical theory predicted, and, therefore, it cannot be used to estimate the ages of asteroid families. Then Williams(1969) and Yuasa(1973) extended the classical theory further.