↑ The axis of rotation is inclined 0.2 seconds from the axis of symmetry, with an observed effect that the axis of rotation moves about its axis of symmetry every ~440days. - Analytic Mechanics, Grant R. Fowles, 1962, Holt, Reinehart & Winston, New York
↑ Telling Time, Nature, Nature Publishing Group, 2006, Volume 444/9, pp. 134
